Electronics Forum | Mon Apr 03 09:58:49 EDT 2006 | PWH
Sounds a little like 2" O.D. pipe with 1" wall thickness.
Electronics Forum | Tue Apr 04 11:51:44 EDT 2006 | dougs
10mil square apertures should be ok with your 4mil stencil.
40731 | https://www.smta.org/smtai/SMTAI-2019-Technical-Program.pdf?v=200609010628
Surface Mount Technology Association (SMTA)