Designed this PTT very similar to the Invisio one. It has 3 working buttons that can be attached from the inside thanks to the 6 supports. The inner space is big enough to host the needed stuff.4 accesses, 2 on the top, 2 on the bottom.Side buttons are dummy.There are different tipes of pin for the cables, print the ones you prefere.

Print it as shown in the photos to achieve the maximum quality, you'll need supports only for the main part. I recommend to print supports every 2 layers to save time and to remove them in a easier way.