I was using ca but just now trying 3m spray repositionable adhesive normally used to mount photos. Not sure if it would withstand casting but I'm just doing a build up of medium ca and it seems to work fine.
I use medium CA. Most of the time it sets up quick enough to roll them out and set aside. Sometimes I use a floss type wax coated string to wrap around them if they don't stay stuck down. Just let them sit for a couple days before casting.