hey really good idea i usually just use a cup and shake the crix in there and feed the crix to my beardies then just leave the calcium in there for the next day. also just remember to get any loose cricket parts out of the vitamins ESPECIALLY if putting them back into your supply bottle because i have a feeling bacteria could grow really fast in vitamins but this is pure speculation
I decided to buy one of those martini mixers (stainless steal) for $8. It has worked great. I just put in the calcium or vitamins. Then I dump in the crickets and put the lid on and shake. Next I remove the small lide and this reveals holes that will let the powder through but not the crix. Then I turn upside down of over the garbage and shake a little more and tap the sides until all the powder is out. Put the small lid on and take off the large lid and dmp the crix into the terrarium. If the crickets were small I think one could hot glue some screen over the holes to stop little ones from escaping.