$1 for Swimming noodles at the dollar store. Use a fillet knife to cut to fit just about anything; carve out cylinders to hold batteries & juice: I cut one that I fit perfectly in the cup holder in the car. I sliced other sizes length-wise to fit in camera cases, a cell phone belt case. Carved out perfect pen length slots to hold batteries, carts, attys etc. custom fitted to a fanny pack and a snap shut eyeglass case.