We have an above ground pool for the kids, and I'm planning to make a more solid base for it, soI decided to quickly put together a ground tamper.
Luckily I had some helping hand, this is again a typical DIY project you can do with your kids, as it is mostly about screwing and some sanding.

The MDF boards will definitely not last years, but it was not the aim of the project, I'll only need to handle approximately 10m2 gravel or sand base, so shall not be any issue.
If needed I can attach some pave stones for additional weight.