Unicomp New Model M - Wristrest - Flexible TPU

This design will only fit the New Model M if printed in flexible material.
The wristrest matches the side profile of the board, with the rear feet extended.

Print it in 3 sections even if your printer fits half the model, so the glue seams stay out of the way in use.
By printing the centre piece last, you can measure the width and adjust accordingly, but keep in mind that the design relies on being slightly stretched to stay snug against the case.
Glue the pieces together with superglue, let this properly dry for a day, away from the keyboard to not leave white residue on it.