This is a hobby that can be done in a small area. I have tried several containers and found this to be the easiest an cleanest way for me.
First you need to find the "wet" floral foam that absorbs water. I cut wafer slices from the blocks then using the bottom 1/2 " of pudding cups, lids or other shallow container; press it into the foam like a cookie cutter.
I then take the Glad press n seal and using only a small piece completely cover it. Using a toothpick I pierce the plastic to allow the foam to absorb water.