Apple Newton MessagePad 2000/2100 AA Battery Tray

My Netwon MessagePad 2100 didn't come with a AA battery tray so it was always tethered when I used it. Original AA battery trays are hard to come by.

Building upon the excellent work by Levi Stanley (niterain) of a AA battery tray for the MessagePad 2x00, I modified it to use an easily obtained positive and negative battery spring bridge easily obtained from a cheap AA battery holder found on Amazon . It can be popped out easily with a flat tip screwdriver. You will also have to trim the left and right bottom corners of the spring bridge to fit in the battery tray.

Printing this model is challenging. My first inclination was to print it horizontally. Unfortunately, the bottom isn't flat so there's a lot of support scaring and it would have needed a lot of sanding. Also, I used the “detect thin walls” function in the Bambu slicer, otherwise the interior of the tray isn't solid/connected. The tolerances on the model are incredibly tight.

Instead, I printed it vertically with the “handle” pointing up (see screenshot). I used automatic tree supports which worked well for printing. But be warned, it still required a lot of excavating of support material, especially at the top where's there's a tiny gap where the spring terminal is slid into. Study the model carefully to know what to excavate and what to leave alone. I used a flat tip exacto knife, needle nose pliers, and a small dentist pick. It was a lot of work.

The negative terminal is the bottom of the battery through the hole on the end. The positive terminal is on the side. I used copper tape to fashion a terminal that threads through the hole to the side. See diagram for correct battery orientation and pin-out.

The first revision I did failed by pushing the end off because of the pressure of the spring. This version is slightly stronger but may still fail after a while. I try to remember removing the batteries after use to avoid the batteries leaking.

Update: My second revision does away with the metal battery springs. The springs provided too much pressure and separated the end cap. Instead I used two pieces of heat shrink tubing wrapped with copper foil tape to provide the spring action. See pictures.

Good luck on your print!