How To Make Water Effects For Gunpla Dioramas

As we learned in Tex Merquise’s guide to competitive Gunpla building, custom bases and dioramas can help your advanced Gunpla build stand out from the crowd. We turned to Emily, who previously taught us how to build a custom mesa diorama and walked us through the steps of her award-winning build Trust You, about adding resin to create a simple—but show-stopping—water effect to your next Gunpla diorama. 

Upstart Epoxy provided us with materials for this tutorial.

One of the most common things I get asked about is creating water effects. For many builders, they can seem like some form of mystic crafting which only experienced hobbyists, who have stared unblinking into the void, would dare to create. Fear not, it’s a much easier process than you may have thought. The following tutorial is appropriate for anyone who wants to dip their toe into basic diorama construction.

For this build, I’m going to show you how to make a small river or creek using a 2-part epoxy resin from Upstart Epoxy. This type of resin is normally used to coat bar and tabletops, giving them a clear glossy finish that is incredibly durable, making it perfect for a diorama.

To start, I built my river bed much like I did the terrain in my Mesa and Trust You builds. The only difference is that while I previously used drywall plaster, this time I used Sculptamold to form the ground layer over foam board. There is no particular reason for the different material this time around; I just happened to have a bag of it laying around.

Whichever material you use for your base, it’s important to seal up the edges of your river in the foam board stage so that the resin won’t find its way underneath the foam and leak out in unexpected places. You can do this by running some wood glue along the edges before applying your ground layer.

Once your ground layer is in place, it’s time to paint and finish it. After the resin is poured, it’s a point of no return, so it’s extremely important that you are happy with how things look before introducing the water feature into the picture. For tips on how to paint and finish the dry portion of the diorama with weathering pigments, you can check out my mesa diorama tutorial.

If, like me, you want to have your water feature going beyond the edges of your project, you’re going to want to build a temporary dam to prevent resin from spilling out all over your table/floor/cat. To do this, simply use some painter’s tape to cover the opening, trim it to size, and run some wood glue along the edge. Make sure your wood glue has good, consistent coverage—resin will find holes to leak out of.

Place your project on top of some cardboard or other disposable scrap that you don’t care about in case of leaks. Start mixing the epoxy resin by following the manufacturer’s instructions. I didn’t have any issues with the consistency of Upstart Epoxy’s resin; it’s a 1:1 mixture making it very easy to mix. I added a tiny drop of brown ink to my mix to give the resin a bit of murky color. If you do this, DO NOT ADD MORE THAN A DROP. It’s very easy to overdo the color and ruin your mix.

Place your project on top of some cardboard or other disposable scrap that you don’t care about in case of leaks. Start mixing the epoxy resin by following the manufacturer’s instructions. I didn’t have any issues with the consistency of Upstart Epoxy’s resin; it’s a 1:1 mixture making it very easy to mix. I added a tiny drop of brown ink to my mix to give the resin a bit of murky color. If you do this, DO NOT ADD MORE THAN A DROP. It’s very easy to overdo the color and ruin your mix.

After fully mixing, slowly pour your resin from a height of about 6-8” above your project to minimize bubbles forming. Generally, you don’t want to do a layer thicker than 1/8” thick at a time, but some resins are capable of going thicker—check your instructions. 

Once the pour is complete, you can run a hairdryer on high or a heat gun a few inches over the surface to draw out bubbles and force them to pop. Do this a few times over the first hour of the cure. Next, wait however long the instructions say to before adding additional layers and/or letting it completely cure to go onto the next step. This will take at least 24 hours.

Okay, you’ve waited 24 hours at least, right? Good. At this point you should have a nice solid chunk of resin that kinda looks like water. Let’s add some wave effects to finish the job. For this step, you’re going to need some gloss Mod Podge and a source of controlled air bursts such as an airbrush, a can of compressed air, or a straw and good lungs. Drop some Mod Podge onto the surface starting at one end. While it’s wet, hit it with a burst of air. 

Repeat this process across the entire water surface and you’ll end up with a wave pattern effect. You can do multiple layers and build up the effect in some areas to create more and larger waves. Just be sure to let the Mod Podge dry between layers. If you’re unhappy with the results, you can peel it off and start again from the resin layer. You can also brush white paint lightly over the high points to make more extreme whitewater effects.

And with that, you should have a nice-looking water feature to show off.

Emily has been building Gunpla for 20 years. You can see her latest builds and terrible anime opinions on Twitter. When she isn’t working at her regular job, 3D printing, or building Gunpla, she hangs around the house with her three cats and husband Matt.