As promised, I'll start uploading tutorials for my Shadowheart cosplay. I'll start small: a few words on the tadpoles. What you need (no link since you'll probably have different brands available) :
a 3d printed tadpole; I printed it myself, took Dark Nyarl's model, but there will probably be other models soon if there aren't already;
everything you need to paint a 3d miniature (primer, purple and gray paints; optionally, some vanish);
a round glass jar with a cork stopper. Those key words gave me nothing in my region, but it got easier once I figured out that the required volume is around 120 ml;
2 component resin. Important: it needs to allow for thick layers; measure the height of your jar - the resin should be poured in in one layer;
greenish resin color pigment. Important: it needs to say that the pigment is translucent. Semi-translucent will not do.
I modified the 3d model's size. The tadpole on the left was 5 cm high and turned out to be too small, so I printed several more 6 cm big. If you can print something at home, I don't need to explain to you how to print and paint it, but if you're asking someone else to print one for you, remember that a miniature needs to be primed before you paint it (there are liquid primers you brush on, and there are spray cans). Here are the colors I used:
You don't NEED varnish after, but the paint will crumple somewhat in the resin later on. It's not really noticeable with a naked eye, but keep that in mind anyway.
Glue your tadpole to the jar from the inside if you want it to stay in a specific position. Be warned that it'll look very chonky once there's resin around it. Follow the instructions for the resin: mix the components as suggested (use a kitchen scale if you have one), add your color pigment and mix it in. It took me 10 drops to get the color you see above.
I tried pouring in several 2cm layers of the most standard reson, and it didn't work out for me, I could see the layers. A pro might know how to avoid it, but a newbie should try to find the kind of resin that can be poured in a 5cm layer of thicker. Here's the old version:
If you want to avoid having bubbles in your resin, research bubble-removing methods in advance if there are no tips in the instruction that comes with the reson you found. Let the resin solidify as per the instruction!