Im assuming this is for feeders. Why not go spend the $8 at the pet shop and get the flukers water stuff? Thats pry what your going to end up paying anyway
i purchased a 1lb bag of water crystals from www.progeckos.com for about $8.00 plus shipping and handling. I assume these are for your feeder insects so you can use fruit in the mean time like a orange slices and carrots for them while you get the crystals.
1) Buy some water crystals ( tiny crystals that will expand when you add water)
2) Add water to a teaspoon of crystals in a cup
3) they will absorb the water and expand
4) once they are done expanding they are ready for your insects.
Note a 1lb bag of crystals will make a ton of water crystals that will probably last a while.
With a couple of teaspoons of the crystals which is not that much i was able to make about a gallon of water crystals. I only used about maybe 10% of the crystals shipped in the 1lb bag to make them.
So you want to make the crystals themselves and not the end product which you use to give water to your insects. If so then i do not have a clue... sorry.