I always liked rebuilding and working on the 'boys' rifles. They could for a long time be found at very decent prices and were good projects. Lots of different makes and variations were made and most saw heavy use. Rebuilding and restoring them to usable condition taught me a lot.

I finished up a Hopkins & Allen Model 3922 single shot 22cal rifle about a year ago. One I had bought way too many years ago as a box of rusted and broken parts at a gun show. It sat all those years till I finally got the time to work on my own stuff! Turned out pretty nice.
I'll see if I can get a couple pictures of it.

Still have a Stevens Model 45 in 22cal in the works. Making it into a Scheutzen Model (52?). Not really a Boys Rifle, but other than the DST and 1/2 oct bbl that makes it a Model 45,, it's a plain Model 44 Stevens single shot. Plenty of those were bought and used as farm rifles.