Want a practical, ready-to-print 150mm f/5 telescope because you cannot find a f/2.8 mirror ? Check out this project instead, that uses commonly available parts and is thought for ease of use : https://www.printables.com/model/1325533-smallest-telescope-kit-for-150750

BOM :

1x primary mirror, 155mm physical diameter, 430mm focal length
1x GSO 4 element coma corrector
1x 360mm vixen-like dovetail
1x 54mm secondary mirror
6x 5mm * 500mm carbon rod (cut to length)
3x 1mm thick, at least 7.5mm large, aluminum plates (focuser plates)
4x M4 * 16mm screw (focuser bearings)
4x 623ZZ bearing (focuser bearings)
4x M4 * 30 screw (focuser mounting)
3x M3 * 16 screw (corrector mounting hub)
2x M5 nylon pressure screw
1x 3mm smooth rod (focuser pinion)
3x 2mm steel nail (mirror cell lever axis)
4x M4 * 45 screw (mirror cell collimation, secondary hub)
6x M4 washer (mirror cell collimation)
3x heavy duty spring (mirror cell collimation)
1x lighter spring (secondary mirror collimation)
1x M4 nut (secondary mirror collimation)
3x M3 * 50mm screw (secondary mirror collimation)
10mm  x 1mm thick carbon flat (spider vanes)
Cyanoacrylate glue
16 M3x12 screws (backplate mounting)