Online there are many and very varied examples of how to keep a machine or two on display (or more than two). Some hard to do, some less hard.
Just realized that the Billy Compatibility of a typewriter is an important factor for easy display. Having a depth that is less than about 30 cm makes it much more practical to keep it on display for a while. This would I guess be a factor for collectors in most countries that have large furniture stores from Sweden with often a whole aisle dedicated just to Billy.
For any next machines, the Billy Compatibility will be an added requirement. That keeps the Corona Four (I think) on the list and of course an Underwood 3-bank.
(More machines would be Expedit Compatible, have however no shelf-space of that type... :)