Storage box for four 18650 cells
A lidded box that carries four 18650 lithium cells with each one in its own bore, so the terminals cannot touch and short in a bag. Each cavity is 18.8 mm in diameter and 66 mm long to fit protected cells with a little slack, with 1.5 mm ribs between bores and a 2 mm outer wall. A finger groove at the top of each bore makes removal easy, and the lid closes with two 0.4 mm snap bumps. Print the base upright so the bores come out round.
With SpeakCAD the box holds precisely as many cells as you carry, in whatever arrangement fits your pocket: two by two, a row of four, or a flat sleeve. Preview free in the browser, then ask for a hinge, a label recess or 21700 dimensions instead.
Design a lidded storage box for four 18650 cells in a row. Bores 18.8 mm diameter, 66 mm deep, 1.5 mm ribs, 2 mm outer walls, 3 mm floor. Finger groove 6 mm wide per bore. Separate lid 6 mm tall with two 0.4 mm snap bumps.