Print-In-Place Ellipse Drawing Trammel
A trammel of Archimedes that draws true ellipses for oval cutouts (speaker holes, van ports, arched panels) — a 150 mm cross base with two crossing T-slots, two captive sliders and a 120 mm beam, all printed as one assembled 4-piece mechanism with 0.4 mm running clearance. Pin spacing is 45 mm; eight 8.0 mm pencil holes along the beam give ellipses from 18 x 72 mm up to 96 x 186 mm overall, and four 4.5 mm holes (M4 clearance) at the arm tips let you screw or tape the base to the panel.
mechanism trammel ellipse print-in-place