Printed a mod of the design posted above. I also designed a split sleeve adapter so I can use the shoe with either a Makita or DeWalt.
Split sleeve: https://a360.co/2GCvPrX
Dust shoe: https://a360.co/2kcASGT
This is changed significantly from the original so I’m guessing its ok to share. Namely, the vacuum passage has been opened up and the lugs for the bolt/nut thickened. I’m no internet lawyer though, so any objections let me know.