Customized version of https://www.thingiverse.com/thing:4316881

Created with Customizer! https://www.thingiverse.com/apps/customizer/run?thing_id=4316881

Using the following options:

track_height = 15
track_width = 20
track_length = 50
slot_width = 8
slot_depth = 12.5
t_slot_depth = 2.5
t_slot_width = 15
t_slot_height = 10
slot_bottom_width = 15
screw_hole_width = 3.5
track_segments = 4