This is a 150mm overall length miniature ball-bearing drawer slide inspired by the Misumi SAR2 series telescopic rails.

This design uses Crosman Copperhead 4.5 mm BB's for the bearings  (but these are actually about 4.35 mm in diameter, no idea why the product lists a diameter of 4.5 mm).

Two M2x8 or M2x6  screws are used to bolt the rail end stop to the outer frame (force threaded).

TWO slide versions are available

Type H:  

Uses M3x5x4 heat inserts for the stroke mounting holes

Type S: 

The stroke mounting holes are sized to force-thread M3 bolts into (if you don't get enough thread bite, adjust XY-hole compensation)

This method of joining 3DP parts gets a bad rep, but it can actually be pretty strong if you size your holes correctly.

Other notes

The larger hole in the stroke is an access hole for reaching one of the outer frame mounting holes.

I have been using eSun PLA+ to print these, but feel free to try other filaments, just be aware that due to different thermal expansion, you may not get great tolerance regarding the spacing between the bearing grooves of the stroke and outer frame.

A bit of lubrication makes these a lot smoother and reduces the problem of bearing binding and dragging along the rail.