7 Mistakes New Gunpla Builders Make (And How to Avoid Them)

Originally published December 2024. Updated April 2026 with expanded coverage of 7 common beginner mistakes.

Gunpla - short for Gundam Plastic Model - is one of the most beginner-friendly hobbies out there. The kits are snap-fit, meaning parts click together without glue, and Bandai's instruction manuals are clear enough that you can follow them without reading a word of Japanese. If you just picked up your first kit, you're in for a good time.

That said, most first builds go the same way. You open the box, start cutting parts off the runners, and somewhere around the twenty-minute mark you notice stress marks on visible armor or realize you just put a left arm in a right arm socket. It happens to almost everyone.

These are the same gunpla mistakes beginners have been making for years, and they're all easy to avoid once you know what to look for. Here are seven of the most common ones - and what to do instead.

1. Buying the Wrong Tools (Or No Tools at All)

This is the most common new gunpla builder mistake, and it usually goes one of two ways. Either you buy nothing and try to twist parts off the runners with your bare hands (we've seen it), or you walk into a hobby shop and buy a bunch of traditional model-building supplies you don't actually need.

Here's the thing: Gunpla kits are snap-fit. That means no glue required. The parts literally click together. If someone told you to buy plastic cement for your first Gunpla build, they were thinking of a different hobby. Traditional scale models - aircraft, tanks, cars - need glue. Gunpla doesn't.

The flip side of this mistake is using whatever you've got lying around the house. Nail clippers, wire cutters, kitchen scissors - people have tried all of them. Nail clippers were actually a common beginner hack for years, and they'll technically get parts off the runner. But they crush the plastic instead of cutting it cleanly, which leaves stress marks and uneven edges that are a pain to fix.

What you actually need: A pair of hobby nippers (also called side cutters or sprue cutters), a hobby knife like an X-ACTO, and a set of sanding sticks in a few grits (600, 800, and 1000 will cover you). That's it. Three tools. You can get fancier later, but these will handle anything from an Entry Grade to a Master Grade without breaking a sweat. Check out our tool collection if you want to see what's available.

2. Skipping the Manual (Or Just Glancing at the Pictures)

This one causes more problems than people realize. A lot of new builders open the box, flip past the first two pages of the manual, and jump straight to whichever section looks like it starts the build. Those first two pages aren't filler. They contain the runner map (a visual inventory of every parts sheet in the box), the color guide, and any symbols or warnings specific to that kit.

Skipping the runner map is how you end up with 30 loose grey parts in a pile and no idea which runner they came from. Bandai labels every runner with a letter and every part with a number - A1, B7, C12 - and the manual references those codes at every step. If you cut parts off the runners before you know where they belong, you're creating a puzzle with no picture on the box.

The manual also flags parts that look identical but aren't interchangeable, steps where you need to choose between options (beam saber drawn vs. stored, open hand vs. fist), and parts marked with an X that aren't used for your specific variant at all.

What to do instead: Before you cut a single part, flip through the entire manual. It takes two minutes. Check that all your runners are present by comparing them to the parts list page. Then build section by section, only pulling runners as the manual calls for them. This one habit alone prevents half the mistakes on this list.

For a full breakdown of how Bandai manuals work, including every symbol you'll encounter, check out our guide on how to read Gunpla instructions.

3. Butchering Parts Off the Runner

The runner (that plastic frame all the parts are attached to) is designed to hold everything in place during shipping. It's not designed to make removal easy. The little connection points between the runner and each part are called gates, and how you handle them determines whether your finished kit looks clean or rough.

The most common gunpla beginner mistake here is cutting too close to the part on the first cut. You think you're saving time. What you're actually doing is risking an overcut that gouges into the part itself, or creating a stress mark where the plastic turns white from the pressure. Both are hard to fix and impossible to fully hide on darker-colored plastic.

Twisting and pulling parts off the runner is even worse. This almost always cracks or warps the plastic, and on small parts - polycaps, tiny armor panels, V-fins - it can snap them outright. Once a part is cracked, you're looking at glue repairs that rarely look invisible.

The right way to do it: Cut each part off the runner in two steps. First cut is about 2-3mm away from the part, leaving a small nub of extra plastic still attached. Second cut trims that nub down close to the surface. Then clean up whatever's left with a hobby knife or sanding stick. It takes a few extra seconds per part, but the difference in the finished build is night and day.

For a deeper breakdown of nub removal techniques, check out our Beginner's Guide to Nubs.

4. Mixing Up Parts That Look Identical

Gunpla kits are engineered with serious precision. Left and right arms, legs, shoulder armor - they often look almost the same, but they're designed to fit one specific way. The pegs, slots, and cutouts are slightly different between left and right versions, and those differences exist for a reason.

New builders tend to assume that if two parts look similar, they're interchangeable. They're not. Putting a left arm in a right arm socket might seem to work, but the fit will be off, the joint will be loose or stiff in the wrong direction, and you'll be kicking yourself when you realize the mistake three steps later and have to disassemble half the torso.

How to avoid it: Before you attach anything, check the part number on the runner against what the manual says. Bandai's manuals are almost entirely visual - you don't need to read Japanese to follow them. The part numbers (like A1, A2, B7, etc.) are printed right on the runner next to each part.

If two parts look identical and you're not sure which is which, dry-fit them first. Just press them gently into position without snapping them in. If it resists or doesn't line up, you probably have the wrong side. The manual also usually shows left and right with clear mirrored diagrams. When in doubt, lay both parts out side by side and compare them to the illustration.

5. Forcing Parts That Don't Want to Fit

This is the mistake that actually breaks kits. A part isn't lining up, so you push harder. Then harder. Then you hear that sickening crack and you're staring at a snapped peg or a split armor panel.

Bandai engineers their kits so that parts only fit one way, and when they're oriented correctly, they click together with moderate pressure. If you're having to use real force, something is wrong. Either the part is backwards, you skipped a step in the assembly sequence, there's a nub remnant getting in the way, or you have the wrong part entirely.

This is especially common with polycaps (those small rubbery joint pieces) and with closing two halves of a limb or torso section around an inner frame. If the halves won't close flush, check that every internal part is fully seated. One slightly misaligned polycap or an inner frame piece that isn't clicked in all the way will prevent the outer armor from closing properly.

The rule is simple: If it doesn't fit, stop pushing. Go back to the manual, double-check the step, look for leftover nub material on the connection points, and try re-seating any internal parts. Bandai kits are precision-engineered. If something requires force, that's the kit telling you something is off.

6. Choosing a Kit That's Way Above Your Skill Level

Every grade of Gunpla exists for a reason. Entry Grade (EG) kits are simple, tool-free, and designed for absolute beginners. High Grade (HG) kits are the backbone of the hobby - affordable, huge variety, and manageable for anyone with basic tools. Real Grade (RG) kits pack Master Grade detail into a 1/144 body, which means small, fiddly parts. Master Grade (MG) kits have full inner frames, more parts, and builds that take 8-15 hours. Perfect Grade (PG) kits are multi-day projects with hundreds of parts, die-cast components, and price tags to match.

The classic beginner mistake is picking a kit based purely on which Gundam you like from the anime, without checking what grade it is. We've literally had a customer buy the Perfect Grade Wing Gundam Zero Custom as their first-ever kit because they grew up watching Gundam Wing and wanted the biggest, most impressive version. That's like learning to drive in a Formula 1 car. It didn't go well.

PG kits assume you already know how to handle small parts, read complex assembly sequences, manage sub-assemblies, and troubleshoot fit issues. None of those skills exist on your first build. Starting that far above your level doesn't teach you faster - it just makes the hobby feel frustrating when it should be fun.

Start with HG. The High Grade line has the most variety of any grade - hundreds of kits across every Gundam series. You'll almost certainly find something you like. They build in 2-4 hours, they look great on a shelf, and they teach you all the fundamentals: nub removal, reading the manual, proper assembly order, and how parts fit together. Once you've got a few HG builds under your belt, jump to RG or MG and you'll actually appreciate the added complexity instead of drowning in it.

For a full breakdown of every grade, what they cost, and who they're for, check out our Gunpla Grades Explained guide.

7. Rushing Through Stickers and Decals

You just spent a few hours building your kit and it looks great. The last thing you want to do is slow down for stickers. So you peel them off the sheet with your fingers, slap them on roughly close to where the manual shows, and call it done. The result: crooked markings, air bubbles, stickers peeling at the edges within a week, and clear backing film visible on every one.

Most HG kits come with foil stickers for eye cameras and small color details, plus marking stickers (the ones on clear backing) for insignias and warning labels. They're not hard to apply well, but they do require a little patience and the right technique.

There's also a timing issue that catches a lot of first-time builders off guard. Some stickers need to go on during assembly, not after. Eye stickers are the most common example - on most kits, the eye camera piece gets sandwiched between the face plate and the head frame. Once the head is fully assembled, there's no way to reach it. The manual will show you when to apply these, which is another reason not to skip ahead (see mistake #2). If you've already closed up the head without the eye sticker, you'll have to carefully pry it apart to get it in there.

Beyond timing, the biggest application mistakes are touching the adhesive side with your fingers (the oils from your skin weaken the glue), trying to reposition stickers after pressing them down firmly (this stretches them and weakens adhesion), and skipping stickers entirely because they seem too fiddly. That last one is a shame, because even just the eye stickers and a few key markings make a noticeable difference in how the finished kit looks.

How to do it right: Use the tip of your hobby knife or a pair of tweezers to lift stickers off the sheet instead of your fingers. Position the sticker where it needs to go, then press it down gently with a cotton swab to smooth out air bubbles and get the edges to sit flat. For marking stickers on clear backing, trim any excess clear film close to the printed design before applying - it makes the sticker look more like a painted detail and less like a sticker.

If you want to take things further down the road, waterslide decals are a significant upgrade over stickers for a more realistic look. We have a full walkthrough on how to apply waterslide decals when you're ready for that step. But for your first few builds, just taking care with the included stickers will make your kits look noticeably better.

The Real Secret: Patience

None of these gunpla mistakes are catastrophic. Builders at every level still occasionally cut a part wrong, mix up a left and right piece, or underestimate a kit's complexity. The difference between a frustrating build and a great one usually comes down to slowing down, checking the manual, and not forcing anything that doesn't want to fit.

Take your time. Gunpla isn't a race. The kits aren't going anywhere, and neither are your nippers. The more attention you pay on your first few builds, the more natural it all becomes - and the better your shelves will look for it.