This is a holder I made for my Hardell Cordless Rotary Tool, but it should fit others of the similar size. The top drawer is designed to hold up to 18 bits, two collets, and a small wrench. It has mounting holes in the back wall of the main structure.

Feel free to copy and adjust the model to fit your needs! https://www.tinkercad.com/things/kxWeDdC0rW3-cordless-rotary-tool-holder