The model
The moving jaw runs on two guide rods, and the screw advances it 8 mm per turn. A retaining fork engages the groove of the screw and pulls the jaw back when you unscrew.
The jaws hold inserts in dovetail grooves: serrated for flat pieces, with V-grooves for round stock. The scale on the base plate shows the opening in 5 mm steps.
All parts print without supports and already lie in print orientation in the files. Even the thread is simply printed along.
View assembly guide (German)
Print notes included in German; part names are self-explanatory.