@PietervanStaden and Raimund. I can offer an easier solution to the stone case building caddis rather than collecting the actual cases, drying them out, cementing them to hooks, and UV coating.
Check out a post I made here called Peeking Caddis and see the top row. All you need do is collect a little river sand/stone on your next trip. No hunting for the actual insects themselves. Then just build an underbody with whatever you like, coat the underbody with superglue and roll it in the sand. There you go, a cased caddis! Add the peeking part if you like and a turn of soft hackle. They work great. One added advantage to this way is you can add weight if desired to hook before building underbody.
Guys, try a hobby shop and look for model train ballast, the stuff the model train guys put under their tracks. You can get ultra fine stones in different colours. They are lightweight as well so you can still control the weight of your fly with lead free wire. Cheers
On FlyFlasher.com you can find 31,739 flies from all over the world. Flash your own fly patterns, upload your current work or search for inspiration. The flies are tagged, so you easily can search for them.