Logo pen
I have an idea to get around some of the problems involved with logos, if it is mechanically feasible.
I'm a retired Army Warrant Officer and anythinig with the Army Warrant Officer insignia (lovingly known as the squashed chcicken) sells to Warrant Officers. One of my COW (Crusty Old Warrant) buddies has a pen wilth a filial that has a domed plastic piece on the top, the dome tends to magnify anything put under it. Obviously, his pen has a squashed chicken under that dome.
I wonder if you could make a filial with the dome not yet atttached and allow the purchaser to print and place his own design under the dome. Perhaps the dome could be attached with a screw, or snap, ring or perhaps just CAd into place.
Even if you can't supply the components for the purchaser to assemble ,,,, could you assemble them with graphics supplied by the purchaser?
In either case, you are not producing and supplying any logos or insignia.