Now having read through the thread I am happy to report your job is much easier than you thought. There really is only one option, the Bottlehead kit. Just reading (studying, and understanding) the description will give the kid a better understanding of hi-fi components than most. It is not that hard, recommended even for first time kit builders and taking no more than an evening or two to build. It does not require any woodworking skills.
https://bottlehead.com/product/reduction-1-1-phono-preamplifier-kit/
This kit is a lot simpler than the Dynaco ST400 I built at his age without any help. The Bottlehead kit is way simpler and yet also a much better project and component.
In the end he will have spent more than planned but he will have a $1k phono stage for $400 and more importantly he will have acquired an actual asset not a money pit car. Important life skills I should think.
If he does this I will not chip in $50 but instead do one better, and send you the Cardas Quad Eutetic rosin core solder to do it right.
https://bottlehead.com/product/reduction-1-1-phono-preamplifier-kit/
This kit is a lot simpler than the Dynaco ST400 I built at his age without any help. The Bottlehead kit is way simpler and yet also a much better project and component.
In the end he will have spent more than planned but he will have a $1k phono stage for $400 and more importantly he will have acquired an actual asset not a money pit car. Important life skills I should think.
If he does this I will not chip in $50 but instead do one better, and send you the Cardas Quad Eutetic rosin core solder to do it right.