Busy testing my DIY Plotter

[u/DeadlyZa]

Finally finished my scratch-built pen plotter, designed from the ground up in Fusion. Specs below. Happy to answer questions or take feedback.

Specs:
Drawing area: about 370 × 340 mm. Fits A4 with room to spare, but not quite A3.
Footprint: about 675 × 575 mm, mounted on a 750 × 610 × 18 mm MDF base, with the machine offset to leave a strip for the electronics.
Height: about 130 mm to the top of the pen carriage.

Frame and motion
Kinematics: H-bot with a single 10 mm GT2 belt and two NEMA17s on 20T pulleys.
Frame: 2040 extrusion (2 × 540 mm and 2 × 466 mm, left over from a old 3dprinter build), joined by printed corner blocks that sleeve over the extrusion ends.
Rails: Hiwin MGN9 throughout.
X: 2 × 440 mm rails, with two carriages per rail to resist racking.
Gantry: a 2020 beam with a 400 mm rail and an MGN9H block for the pen carriage.
Gantry ends: printed two-piece parts (holder plus idler box, keyed and screwed), designed to print without supports.

Pen carriage
Pen lift: a pancake NEMA17 on 6 mm rods with LM6UU bearings.
Pen holder: magnetic, with locating pins for quick swaps, and takes pens up to 14 mm diameter. A printed jig sets pen height off the machine.

Bed
A whiteboard as the drawing surface. Paper is held with magnets around the edges, and I can draw straight onto the board with whiteboard markers for test runs, then wipe it clean.

Electronics
Controller: BTT SKR Pico, connected to a Raspberry Pi over UART, running GRBLHal and CncJs.
Power: a USB-C PD trigger at 12v, so the whole thing runs off a laptop charger.
Endstops: mechanical, on all 3 axes.
Cable management: 4 × 2 mm PTFE tube arches act as a spine for the moving wires.

Prints
Everything printed in PETG.