remove sticking parts from calipers using metal handsaw
Dissasemble the calipers and remove depth gauge part
drill 3 holes with 2mm drillbit in the center of the caliper display back plate, so the screwheads fit in the slot originally used for the depth gauge
Transfer those holes to the alluminium plate, and drill them with 2mm drillbit as well. The ruler part of the caliper should move freely.
Transfer also holes for assembling the calipers body but drill them with 3mm drillbit, so you can assemble the calipers back again when mounted to the alluminium. The bigger holes allows you to secure screws through aluminium plate.
Cut off sticking part of the digital calipers (the length of it should match lengt of alluminium plate
Create slot for the metal sheet in the drill press plastic cover. I've used wood router.
Drill holes in the alluminium plate to match holes in the cover and secure them together.
Mount 3d printed collet on the drill
transfer holes in the collet to the digital calipers and drill them… than join with M3 screws.