PTFE 'Bowden' bearings

Technically a bushing-
It is 100% tool-less, and snaps into place with a firm push. A 1/4" piece of 4mm x 1.75mm PTFE tubing costs less than one penny, and makes up one small insert. They can be arranged in any way imaginable. They can be solid, hollow, or filled with a lubricant. They could potentially even be pressurized for dispensing lubricant, or could contain a dye to show when they've worn out. The same bearing can fit both round, and square profiles. Solid state bearings are nothing new, but they have never been this easy or cheap to work with.
I would love to see what people come up with. The included files are just to convey their basic operation, you will have to design yours to fit the profile you're working with. If you don't have the design skills, please contact me, and I'll see if I can design it. I will have a 20x20mm Open V-Rail bearing profile available in a couple of days.