Here is one I made for storing tanks and a couple of eGo-style batteries, for a fellow member... It is made with a 4x6 piece of scrap Poplar, holes drilled, and the round eGo stands are round closet door knobs I picked up in a box-lot some years ago... everything sanded, stained, and sealed with satin polyurethane.
I've made several more of different sizes... using scrap wood... This 4x4" block holds 16 tanks up to 23mm size, and still has room between them for EVOD size (16-18mm) tanks (and you can also see another re-purposed door knob glued to a small disk which was left over from cutting a hole):