I started to assemble a version of the Mk 19 radio aerial base out of styrene plate and tube, before Enginepeter displayed his amazing expertise.
It was pretty much to scale. It began like this:

- Radio aerial base
That's 1.3mm tube inserted into 3mm tube, mounted on 1.5mm styrene plate.
Then I added the four arms (1.5 mm styrene strips) at 90 deg intervals. So far- so...well, ok.
I made the 'halo' part of the radio mast's protective cage out of styrene strip. The idea was to bend the arms out, and bond the strips to the halo. Ok in principle..but the best laid plans, eh?

- Comet-No 19 radio aerial base-B
But bonding them required octopus fingers. In the end, it was all too fragile.
Then these beauties arrived in the post from Peter himself (what an absolute gent, and genius!!)
Now, potentially I could have the first Quadrophonic Comet RT set in existence!

- No 19 Radio quadrophonic aerials...

Which to use, hmm? Well, the ones with turned brass would be the obvious choice, but the halo might be a tad weak. The others are PLA, I think, and perhaps not as fragile. We'll see.
Then I made a mount for the Commander's gunsight:

- Comet-mount for Commander's gunsight
Taking photos of white objects seems to be a problem for my iPhone 8 +. It's hard to compensate for, post pic. Still, you get the idea.
Here's the unit mounted:

- Commander's gunsight mounted

Finally, with generosity unbounded, Peter also supplied some fire extinguishers:

- Comet-fire extinguishers.
They'll come in very handy on the Cromwell

This Forum attracts some amazingly creative, and generous, people. I only wish I could be one of them.

"Get your facts first, and then you can distort them as much as you please"- Mark Twain.