With “honeycomb” I mean a structure of adjoining (cylindrical, not hexagonal) cells.
Those who know of geometry could explain why (I suppose it is related to the concept of hexagon circumscribed in a circumference), but just by observation, it is a fact that whatever the diameter of a cylinder, the circumference can be filled with SIX cylinders of the same diameter, which is the basis of these racks.
They are made with reused items:
1) Arts and crafts tool rack. Made with tablet bottles and a container
2) Putty and gluing tool rack. Made with Crazy-glue containers and a deodorant bottle
3) Wooden dowels. Made with caulking tubes and a coffee can