We used to make tanks out of cotton reels. They were wooden cotton reels and we would tap a couple of panel pins into the side of the reel and then attach a matchstick and a rubber band, and when wound up that would produce a slow unwinding which would drive the "tank" forward.
Another use was to tap four panel pins into the end of the reel. forming a square round the hole, and to attach an end of wool to one of the pins: we then used a bodkin to feed wool around the the pins in a subtle way and eventually there would appear a woven 'tube' of wool out of the bottom of the reel' hole.
Make a cardboard disc and colour it up a bit, then make two hoes near the centre and thread string through them to make a loop. You could make the disc spin by gently pulling and releasing the loop between two fingers (different hands).
My first penknife I bought on holiday with saved-up pennies. Mam said " be careful not to cut yourself." I knew that penknives were not very sharp, so I tried the edge on my thumb and cut myself. I felt an idiot.
We went through a phase of playing 'Matchbox Rugby'. An empty matchbox cut in half and then pieced together and you would take it in turns flicking it on the outlines of a rugby field in chalk on a suitable flat surface. When you scored a try the defending team would make a 'H' out of their fingers while you try to flip the matchbox over to get the extra points.