I'm really feeling it!

Customizing Gunpla - part 2: model kit surgery

In which we (sometimes) start to cut, sand, putty or glue the model kit into something different.

Last time, I discussed the process of picking out a kit for a custom Gunpla using my own custom as an example. However, as I pointed out, while the Lunagazer has some great qualities, it also has some...unsightly ones as well.


Like those horrible, sharp edges everywhere. So the first step is to sand them down! Sandpaper is one of the best modeling tools because sometimes you need to buff out a scratch or make a surface smoother for paint application later.

For those unaware, modeling sandpaper is of much higher grit than the usual sandpaper we think of. If typical sandpaper for, say, sanding down a piece of wood is about 100 grit, sandpaper for modeling is around 600+, even going so high as 3000. The lower the number, the coarser the sandpaper, which is sometimes needed when you need to get rid of excess plastic.

Or getting rid of sharp edges.

Ok wow, now that I’m looking at this close up, I was merciless with the sandpaper...

In the above picture, you can see the unaltered skirt half on the left and the sanded down version on the right. The right side has less harsh sharp edges than the left, which was the aesthetic I was going for. There’s also a bit of putty used to lengthen the skirt as well. When sanding, it’s important to start low and go high. So for the above example, I started with 500 grit paper, and only did a few motions to get the curve, then moved up to 1000 and 2000 grit to smooth out the surface. Having a smooth surface is more aesthetically pleasing, in most cases.

Side note: hobby sandpaper can get pretty expensive, but you can also use the sandpaper you can buy in hardware stores, just make sure the grit is appropriate. Also note that, from my experience the grit shown will be a bit lower when applied to model kits, so sandpaper that says it’s 1000 grit maybe around 900 when used on plastic models. Of course, when you buy 2000 grit, it doesn’t matter that much if it acts like 1800, it’s still polishing as all heck.

Hobby sandpaper sometimes comes as sticks so it’s easier to achieve level sanding. You can also make your own sanding sticks by gluing sand paper to popsicle sticks!

Putty is also a very useful tool to make new shapes or mods. I personally use the brand Milliput because it’s easily available and cheaper than Tamiya, but use what you like. Most importantly, Milliput is a 2 part epoxy putty, meaning you mix the two parts it comes in together to create the usable putty.

Terracotta is brown and more for bricks and flower pots. It’ll all get painted anyway.

When using the putty, you may choose to add water to help smooth it out, almost like with clay! The difference is the milliput will air dry rock solid, at which point we can sand or drill as necessary.


For our custom Lunagazer, I wanted to have round shoulders because Pearl does not have sharp shoulder designs. Of course, it’s still a mech, so the shoulders will still be super prominent (compared to Pearl’s design).

Half the Lunagazer customized.

In the above photo, you can see a few of the changes that I made. The most prominent change are the shoulders - I got rid of the thing sticking out and instead made the entire thing rounded. The putty used was still Milliput, but a different color. All the same thing.

Careful observations will also see a couple of other changes - the backpack no longer has the long wing but instead has piping. The feet are also different, I opted to use the flat option parts instead of the heels. This was because, as mentioned previously, the Lunagazer model kit has a lot of extra parts so I could get away with it. Otherwise, I would’ve had a lot more work to do. The final product has two more mini changes that aren’t reflected here, but that’s for later.


In tomorrow’s post, which will be the last in the series, we’ll discuss the next step after all the model kit modifications - adding custom color!

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