[Closed] Jump ramps for a (almost) 5 year old.

Made some ramps out of some bits of chipboard and bricks I had in the garage yesterday and today (today the first thing he said when he got home from school was "Daddy, can you make me the ramp?") Would like to get something a bit better for Xmas, which I don't have to supervise the whole time to make sure it's not falling apart (our neighbour's 5yo who isn't nearly so competent on a bike was out rolling over it tonight).

Any suggestions? All I can find are rather expensive at £40+, and also rather bigger than I'd like. Is the best solution to make my own out of some proper bits of wood?

(yes I know I'm an irresponsible parent encouraging my kids this way - but I also want something I can practice my uni on 😉 )