Gel comb for electrophoresis (multiples sizes - parametric)

A parametric gel Comb for electrophoresis

multiples files are provided :

10 wells : 8mm x 2mm 

14 wells : 6mm x 2mm & 6mm x 1.5

20 wells : 4mm x 1.5mm & 4mm x 1mm

Whatever size can be made modifing variables in FreeCAD.