So my take on the best 3d printers for our kids or ourselves is the ones we have to assemble. Just because of the maintenance and failure rate of these things even today. It is far better to teach our young'ns about the workings of a printer so that by the time you have a working machine even your kids understand how to level a bed or adjust the belt tension or adjust forward current to a stepper driver or check for play on a given axis, etc. It is with this mentality that I had all 3 of my kids help me assemble the first printer I bought from here 4 years ago now.
Split the idea in two if you can - the design process and the printing. You can outsource the printing part to start off with. As for design, well it's easy enough to purchase a design and then use some CAD software to play around with it while you build up your knowledge.
If you don't have CAD knowledge try a course, maybe your local Institute of Technology might be able to put you on to a suitable evening course.
I'm sure it would be a great project for kids and adults alike.
