Book shelf pin hole jig drill alignment tool

there are many store bought shelf pin jigs available but most of them are expensive so I simple designed one myself.

Typical shell pins are 5mm in diameter but the jig has 9.6mm holes. This is because it needs to be used not with a 5mm drill but with a self centering drill. The self centering drill I bought has a 9,6mm outer diameter and a 5mm drill. Using this I won' t damage my jig while drilling.

I bought this one from aliexpress:
https://www.aliexpress.com/item/NEW-2-Sizes-HSS-Brass-