Thanks again for the positive comments...
I recently asked elsewhere about a figure to pilot a monowheel, and having done so, realised that I hadn't put any pictures of this vehicle yet.
A while back, Tin Shed Gamer said that you can make almost any kind of model out of card, at the same time as making a rather spiffy monowheel, out of whitemetal, so I decided to try the theory out.

I may have turned up the Bonkers Factor in my version.
To start with I made the circle of card seen above, started with one strip around an old aerosol can lid stuck down with a bit of masking tape, then added two more pieces to make it solid. This is what passes for technology on my workbench.

Next step was to make a rather rough tread, which I’m sure will look fine once it’s painted and weathered and viewed from a distance. Quite a considerable distance admittedly. It probably looks worse to Frederick.

Then I added an equally rough ‘gear’ or possibly ‘rack?’ on the inside of the wheel, which took a bit of fiddling about with superglue to stop the layers from separating. I need to find a better way to do this. I’m told Shellac is the stuff.
‘Colonel’ Oliver is taking an interest, which is Probably a bad sign. Frederick remains unimpressed.

The crowning loopiness so far is the drive unit, which is gradually taking shape. I have a sneaking suspicion that switched on it would rotate inside the outer wheel while producing absolutely no forward motion whatsoever, but we’ll ignore that.
This is also the source of the problem about the driver: Normally the driver would straddle the motor on a monowheel, but on this Behemoth they'll have to be to one side to make space for all the gubbins in the middle, needed because this is a
steam powered monowheel, obviously, so I'll have to think a bit about how I make that happen...
More silliness will undoubtedly follow, but hopefully I’ve now broken the model making block and can get on with some more ‘serious’ models…