I created this as part of heat press and Vertical drill stand a want to create. I added the step file of the rail for anyone that needs it be customized.

Matarials used:

• 6x M3 Nuts 
• 6x M3x20 Screw (4x Countersunk 2x cilinder)
• 46 x .0177inch or 4.5mm BB Balls
• 4x M4 Inserts

Steps (see pictures):

1. Add M3 nuts first before closing the guide (clear the holes if necessary)
2. Add the M3x20 screws in the tension holes (side of the base)
3. Add M4 heat inserts in the base
4. Add the rail into the base
5. Seal of the rail with the clips (slide them on) The BB balls will fall out if you remove the rail from it's guide after assembly!
6. Add the bb balls (23 per side) and close the guide with the covers. Easier to close one side at a time.
7. Tighten the tension screws untill bearing clearance is as you wish for.