This could be hard to find, but if you look closely, there’s a big resemblance with the radio shack 160 in 1 kit.
Only the amplifier seems to differ and 2 npn transistors instead of pnp transistors.
Here’s a link I found to a website where you can even find a download link to the manual of the 160 in 1 kit :
https://medium.com/@rxseger/electronic- ... a39e6193f4
Maybe you can see this as an opportunity to write your own manual !