I've been looking at a slew of different approaches/materials to cover design over time (usually near fall when we're wrapping up clean up in the garden and I remember it's that time for the heat to kick in again). More so of late because half of our radiators are under windows, and that's where the cats want to be. They get none too pleased when the heat kicks in and it's a bit too toasty.
When we closed on our home, we found two metal radiator covers in the garage and none in the house. We thought they were in the garage because they were a bit rusty. (A finished piece of wood that was likely used as a top for one radiator we saw in a listing photo vanished by viewing and did not reappear on the property by closing which was a bit baffling.)
When we measured them to figure out what rooms they belonged to, they didn't fit any of the radiators--either too small or way too big, depending. So now we're wondering where they came from. Could be someone found them curbside.
I personally prefer ones with wood framing as you built because less chance of "ouch!" moments if you brush up against one when they are at their hottest. Wood covers with the metal screen inserts also remind me of when I was a child. My dad constructed a built-in that spanned the entirety of one outside wall of my bedroom which included a cover for the radiator and framed the windows above it in the center. A long shelf ran across the very top, and adjustable book shelves ran down both sides with the bottom sections below the level of the top of the radiator cover having sliding doors for toy/science kit storage and such, and on the right column he made a small pull down desk of the shelf area just above the sliding doors where a solid piece piano hinged to the shelf held closed with a hook and eye, and when pulled down brass chains inside held it flat in place where I did homework or crafts (fashion plates!) until I outgrew it. Recalling those details reminds me of how I got into woodworking--from helping my dad with various projects once I was old enough.
Cane is something else I've considered. If I do the multi panel style front for the downstairs bath, that would help with the size limits. What I typically see available is 24", some styles in 36", and one site has mostly 24" on average, but will allow orders of 36" or even 48" width. That last shop is actually here in MA, so it'd be nice to be shopping more locally as well.