https://www.amazon.com/gp/product/B01HIIFFH4

I can use the odd diameters.

Seems the case plastic is soft, making reinserting the small bits a chore
(maybe some silicon/Teflon lubricant will help, if it lasts).

The bit holder extender has a much more powerful magnet than other cheapos.
Yea!

My grinder and drill sharpener turned the other (wood?) 8 mm bit into an extra
bit to be used on aluminum.

Apparently the same cannot be done to the masonry bits since their flutes are
dull.