Well, buying premade molds is far more expensive than the silicone usually. I suppose you could try the wish molds, though they are not the best quality and the dice made with them shouldn’t be sold due to stolen designs and drama. Here they are anyway. And if you want resin that is kind of possible to get to look good without a pressure pot, here.
Ok so here is the full list of stuff I've bought thus far for the exoterra build, and i'll try and link some of the remaining stuff I need to get. I'll try and put an explanation next to each product. The only reason I did all of this on Amazon is due to the plague thats going around, if you have a local hobbyist or mom and pop shop you can purchase stuff from I very strongly encourage you to do so!
1- Egg crate/light diffuser x3 https://www.amazon.com/gp/product/B078Q2N1BC/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1 unfortunatly I had a hard time finding this material at an affordable price on amazon so I settled with this. The sheets are small so I had to buy 3 sets!
2- Slate for waterfall https://www.amazon.com/gp/product/B07C9VP3MM/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1 I got the five Ib pack of this, it was just barely enough for my waterfall feature.
3- Great stuff expanding foam https://www.amazon.com/gp/product/B001AQ0FVC/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1 This was also for the waterfall feature, works absolutely fantastic! Once it starts to harden it holds my slate in place making a natural looking piece.
4- Aquarium safe silicone https://www.amazon.com/gp/product/B0002ASD2K/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1 lots of functions for this, can be used to seal your background, adhere the background to the aquarium wall, secure decor etc.
5-water pump https://www.amazon.com/gp/product/B076V6J44D/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1 pump for the waterfall, I haven't tested it yet but will report on my results when i do.
6- Zip ties https://www.amazon.com/gp/product/B078NT5F2B/ref=ppx_yo_dt_b_asin_title_o04_s00?ie=UTF8&psc=1 These are for securing the eggcrate together and securing the mesh to the false bottom and waterfall.
7- Clear casting epoxy resin https://www.amazon.com/gp/product/B07BM9LHRB/ref=ppx_yo_dt_b_asin_title_o04_s01?ie=UTF8&psc=1 this is what I will seal the waterfall and background with once the foam putty and painting is completely finished.
8-Window screen mesh https://www.amazon.com/gp/product/B083NPV66H/ref=ppx_yo_dt_b_asin_title_o04_s02?ie=UTF8&psc=1 This is a barrier to keep detritus and critters from going under your false bottom, you can add an additional layer of it to help keep dirt from going through into the water or use fabric weed barrier.
9-Foam sheets https://www.amazon.com/gp/product/B00B8A9188/ref=ppx_yo_dt_b_asin_title_o04_s03?ie=UTF8&psc=1 I initially planned on carving the entire waterfall fixture and background from this material but changed gears when I saw someone use the great-stuff foam and slate method. I still plan on using this for the background portion. Keep in mind this comes with a ton of foam. Like holy crap I should have read the dimensions better, I could make a background for all my tanks and have some left over!
10-Foam putty https://www.amazon.com/gp/product/B0006NARV8/ref=ppx_yo_dt_b_asin_title_o04_s04?ie=UTF8&psc=1 This is a plaster like material that i'll use to smooth over unnatural crevices and bubbles in the foam background and waterfall, then it'll be painted.
11-hydroballs https://www.amazon.com/Zoo-Med-HydroBalls-Lightweight-Terrarium/dp/B00167TXY0/ref=sr_1_1?dchild=1&keywords=hydroballs&qid=1586826444&sr=8-1 this will go beneath the false bottom for biological filtration