Keys for Comptometer

Replacement keytops for Comptometer models C-light through to early M. Especially for model J, where keys are often degraded and/or missing.
 

The keys should print fine on an FDM printer without any support or brim/raft. Precision of a 0.4mm nozzle is enough for good keys to be printed. For best results, the layer-height should be adapted - smallest possible layers at the top and use thick layers at the expanding overhang just under the octagonal section to prevent drooping - see image.

To match an existing machine, keys can be painted and smoothed. Alternatively, keys can be spray-painted with a clearcoat varnish. Apply 3 or 4 layers, this helps mask the layer-lines and prevents lettering-paint from creeping into crevices.

Advised to use latex wall-paint to fill in the lettering. After drying, the excess can be wiped off the keys with a damp cloth that is held taut.