Here is what I need help with.. my Taranis has no “issues” (other than its Frsky).. got Hall effect gimbals, ect.. and after the Frsky BS, I got the crossfire external module.. the RXs arnt cheap and sometimes hard to locate. I’m considering adding ELRS to my bag, get familiar with it, and get some small quads o have off D8.
I know it is as easy as swapping the module out of the bay.. but I was looking at printing a JR bay module that would allow mounting TWO nano external modules..
Fairly simple with a 3D printer.. NOW, the big question.. WIRING.. I’m looking for a switch that would slow you to to only make contact with one of the two modules at a time .. is there one? I know the ground wouldn’t matter, and it maybe just as simple as the power lead..
Can anyone offer some suggestions?

At least for Crossfire, you will need to feed to connect all 5 pins from the JR bay. As mentioned, ground doesn't count. So you will need a switch with quad triple Poles single toggle. 4PST

Edit: let me correct myself

4 Poles double throw (4PDT)
https://a.co/d/dpoX2D3

Pretty much EXACTLY what I’m looking for..
Now to find time to figure it out, get it Printed .. and make sure this switch isn’t easily bumped ..

If you are only using Frsky and ELRS, why do you need dual external modules? Frsky runs on the internal module.

If you did want to switch between two external modules, a quad two-channel multiplexer chip might also work, but maybe that just complicates things.

Rob has FrSky on the internal module but also wants to connect both a TBS Crossfire and an ExpressLRS module externally.

You might be able to connect all the wires in parallel and just have the positive voltage connection on a switch (i.e. an SPDT switch). Then power will only be switched to one of the modules. The powered off module shouldn't in theory do anything as it's powered down, but you would need to do some testing to confirm that it doesn't interfere with any of the communication data going to the powered on module. Only needing an SPDT would be a much simpler setup.