Model originally uploaded to Thingiverse at https://www.thingiverse.com/thing:4287865.

I designed a mount for the bullseye accessory slot to the left of the fan duct. It should hold a standard cutter knife holder with a 11.5mm shaft. It allows some height adjustment to get the knife at just the right height.

Print at 45 degrees with the angled face flat to the bed. Some supports are needed for the circular part