I lost my adapterplate for my old tripod. Before throwing the tripod away, I started to experiment with OpenSCAD and it turned out to be pretty usable.
With the included OpenSCAD-files you can design an adaptermount for your own tripod.
Attached are two versions that show the possibilities of the script. Adapterplatte.scad is preconfigured for a Unomat tripod including two notches on top. Adapterplatte_Fotopro_Digi-3400_Pro.stl is for a Fotopro tripod bought on Amazon. Same file but different parameters.
Just add a standard cameramount-screw (available on ebay).
Anycubic Kossel Linear Plus
If topplate is bigger than the foot, place model with topplate facing down on buildplatform. Else foot is facing down.