Hypercube Evolution X-carriage - 10mm x 16mm sleeve bearings

!!WORK IN PROGRESS!! This is a slightly modified version of the X-carriage for the [HyperCube Evolution](https://www.thingiverse.com/thing:2254103) by [SCOTT_3D](https://www.thingiverse.com/SCOTT_3D/about). Since LM10UU simply won't fit inside the carriage without modifying the center-to-center distance on the original bearings, and the entire rest of the printer really wants 10mm rods, I've bored out the bearing channels to 16mm, which allows you to use 10mm ID x 16mm OD PTFE or UHMW sleeve bushings from McMaster-Carr. PTFE/UHMW sleeve bearings are best used for softer rod materials like aluminum or carbon fiber tubes, which are much lighter and plenty strong, but will get chewed right up by normal LM8UU or LM10UU with hardened steel bearing balls. Either bearing material will function better if lightly lubricated. Grease or oil may attract dust and grit, which over time will wear out the inside of the sleeve bearings and make the X-carriage not be properly constrained; howeve