If there's someone with at least a little tech/mech inclination available to supervise, perhaps a 3D printer might be considered? There are sub US$200 printers available (e.g. Creality Ender 3) which are a good starting point (though you can spend more to get something more plug-and-play) and it presents so many avenues of exploration. There's the mechanical aspect of the printer itself, but also designing things to print (e.g. tinkercad.com) and then getting to hold them is a blast. Even finding pre-designed objects online to download and print is rewarding (see printables.com for inspiration).
Admittedly 8yo is a little young to start. There are challenges, and patience is a must. But the family can find a local makerspace (or library, or school) to get a better idea of what's involved.
Admittedly 8yo is a little young to start. There are challenges, and patience is a must. But the family can find a local makerspace (or library, or school) to get a better idea of what's involved.