Simple mod of the rear cap of the laser telescope collimator (comes with many Newtonian models) making it work from an external USB powerbank. Built around the micro USB PCB ($0.75 per pair off eBay) pictured. Fully Reversible (no stock parts modifications necessary).
See for more details: http://www.dobmod.com/2018/08/laser-collimator-external-power-mod-2.html
Print both parts on the cap's top. Skirt is optional but helps with ABS.
ABS is better than PLA as it might be exposed to the extreme heat from the Sun.
May need sanding the drawer for a snug fit.