I have a spare PC that my sons sometimes use to play Elite Dangerous with me when they visit (and also as a backup for my main PC).

The computer desk has very limited space and it's uncomfortable using the Saitek X52 HOTAS setup on it, so I designed up these mounts to fit the chair arms:-

Each side is a mirror image and is made of 3 sections (my printer build platform is slightly too narrow to do them in two parts.

The main platform and outer armrest mount have to be glued together:-

Here are the completed parts - notice the addition of a thin piece of rubber on part C to increase the friction grip on the armrest:-

The semicircular mounts fit nicely on my chair:-

A single self-tapping screw is enough to hold it in place, though the two parts only come together fully when the HOTAS parts are screwed down:-

Here is the completed setup:-

As the PC naturally sits on the right of the desk, it's not in the best place for the USB lead which comes out of the throttle side, so I looped it around the arms and under the seat along with the stick connection lead. This left the USB plug hanging down about a foot from the chair seat, so I used a 1.8m USB extension lead to attach it to the PC.