Having trouble finding a bushing for a 5 mm bit- or perhaps just not using the right keywords or just not sure what size bushing to get.

I need to make a template for some repeated drilling that would place 5 mm holes around the corners of a square template, so I need only 4 bushings to place in the template. Can someone let me know what size would work without binding the bit and providing good accuracy? A source would be even better.

As a side note the size could be slightly larger or imperial if it's easier. Up to 3/8 inch. I chose 5 mm simply because I have that bit already. I see some dowel drilling guides that have a bushing and bit, but they of course only have one bushong and I need the 4.