
There are different STL files based on if you are using MX Kecaps or reusing the TI-99 ALPS keycaps.

I do not have a mitsumi keyboard so I did not make a keycap adapter for the mitsumi.  You may be able to use Troy's from his keyboard project but it may need modified for height.

https://github.com/visrealm/keyboard4a99/tree/main/doc#bill-of-materials

Brass Inserts I use: https://a.co/d/0aoJ4pPz

MX-99 with MX OEM Keycaps:
For using the MX keycaps you will need to choose a left and right bracket from the MX folder.  One will use just self-tapping screws like the ones already used with the original TI keyboard.  The other will need the brass inserts (3 for each bracket).  The brass inserts the brackets are designed for are M3 threaded, and are 5mm OD x 6mm Length.  A 6mm M3 screw is plenty long enough.

MX99 using TI-ALPS keycaps
For using TI-ALPS keycaps you will need different left and right brackets, again you can choose between self-tapping or one that utilizes M3 machine screws with brass inserts (3 for each bracket).  The brass inserts the brackets are designed for are M3 threaded, and are 5mm OD x 6mm Length.  A 6mm M3 screw is plenty long enough.

In addition to the brackets you will need to print the below:
48 x ALPS to MX adapters
 3 x MX Keycap Extender Adapters
 3 x MX Spacer (spacers will be used on the backlight, backspace and spacebar keycaps which are MX - these are required to blend them into the bottom of the ALPS keycaps.

When inserting the keycap adapters, if you look closely you can tell the box is a rectangle shape on the adapter.  Those go on where the long part of the rectangle shaped adapter goes from left to right, this ensures it will travel the full distance of the key-switch and go inside the switch housing when pressed and will not bind up or be blocked.

When installing the spacers, the spacer will go on first ensuring the notch is at the top of the key to allow the LED to shine through, then install the adapter onto the key-switch, last the MX keycap.

https://www.shift838.com


 