Thank you!
I don't believe that Stapleton would sell you just the arm but it doesn't hurt to ask him. As for the Medical electronics, you can contact GM Props for pricing. Just remember that you will have to modify your existing Science kit to accept the arm, if you get the arm only from...
It's been a while since I did one, but I remember just using simple 3M Spray Adhesive. It left no bubbles at all and was easy to clean up any residue before and after it dried.
As for the main screen graphics, I actually used a piece of silver Mylar paper behind the graphic to diffuse the LEDs...
From my experience, I find that the paint and the clear coat cure so much quicker and cleaner on very hot and humid days. In the winter when it is colder and there is more dry moisture in the air, the paint takes much longer to dry and it remains tacky for a while. Same goes for the clear coat.
To be honest, Gerry, that was what I had to get better at. The building and shaping and sanding to get the bodies perfect is easy for me. The painting (and knowing what weather is best to paint in -- summer humidity!) took me a while to perfect.
That was the first Tricorder build I ever took on. It's pretty labor intensive. I completed a total of 4 of them before I decided to move on. Best of luck!
I have found a way to make the arm on the Star Trek Voyager "Endgame" Medical Tricorder completely independent from the rest of the electronics. The video below shows the first one built in action that also includes my created screen accurate opening, closing and scanning sounds
Star Trek...
The Tricorders you see of mine on my YouTube channel I built myself. They do not come pre-built. There are a few here and there that I got from somebody else, but that was years ago. Pretty much the phasers and Tricorders you see on my channel from the past year were all built by myself.