Having made similar sling mounts for my Walther Century I decided to do the same for my Weihrauch HW77.
The rear mount is made from high grade 3mm aluminum and a pattern being made in card from the rubber but pad remembering to add on a section at the bottom for your sling stud mounting (or bath chain mount). The outline was cut out using a mini hacksaw and then filed to be flush with the stock. As used for the Walther, a bath plug chain mount was used for the sling connection drilled out to 3.5mm to take the QD sling mounts.
The front cocking lever mount was made from brass strip bent to shape around a suitable sized metal bar and mounted using insulting tape layers to protect the finish.
All fastenings used were stainless steel.