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This instructable explains how to make a CNC pen-lift from an SG90 servo, two 4mm x 100mm nails, the spring from a ball-point pen, and a 3D printer.

The design accommodates pen diameters up to 14mm.

There is no pen-wobble when the pen is raised and lowered.

Construction is easy … all you need is access to a 3D printer, and basic workshop tools.

All STL and gcode files are supplied.

The estimated cost to build this pen-lift is less than $5.00 USD


The SG90 servo, complete with horn and mounting screws, was obtained from

The following items were obtained locally

1 only M4 x 20mm bolt
1 only M4 nut
1 only ball-point pen spring
2 only 4mm x 100mm flathead nails
The yellow items were printed on a Voxelab Aquila 3D printer using 1.75mm diameter filament and a 0.2mm nozzle.

The 3D parts were designed using FreeCAD 0.2.

The STL files were created using Ultimaker Cura 4.13.1”

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