Custom synth design idea dump

I've zero experience when it comes to making any kind of hardware, but I can still dream of making a custom synthesiser, can't I?

Adding to my bucket list: making any machine capable of making musical sounds.

Old radio i found in a mountain hostel in Duszniki Zdrój
EQ section of my grandma's tape & radio player

TODO: what synthesis method should it utilise, what sounds should it be able to make?