reverse bowden for Prusa MK3, Bear Upgrade and Zaribo on IKEA Lack enclosure

This is a reverse bowden setup for the Prusa MK3, the [Bear Upgrad-ed](https://github.com/gregsaun/prusa_i3_bear_upgrade) or Zaribo extruder in an IKEA Lack enclosure. I used 2 M6 4mm Fittings and a 2mm/4mm PTFE tube. You need to drill a hole close to the spool holder through the table. Then put the cylinder on it from the outside and the printed tube through the hole in the cylinder and the table and secure it from the inside of the enclosure with the printed nut. After this screw one f