I used to play with this puzzle when I was a kid. Loved the thought process behind it. Hope you enjoy it as much as I did. I got this puzzle originally as a gift. I broke some of the pieces, now thanks to 3d printing, I get to recreate it once more.
Original credit for coming up with the puzzle in the first place: Dr. Vladimir Krasnoukhov.
The author marked this model as their own original creation.