It is inevitable to get inspired by (hardware/software) designs other people make or published somewhere. Sometimes it is not clear who the true designer is, but if it is I try to refence them whenever I base a design on (part of) such a circuit and publish something about my build.
The last 2 designs I made are based on review videos of some module I saw on youtube. I designed the circuit I thought one would need to implement the functions shown and then build it. I have no clue whether the method used in the original circuit is in any way similar to mine, but I do have my suspicions. The 1st I published here was the Sequential-Switch-O-Matic, which is not unlike circuits you find in the application notes of the ICs I used. The next will follow soon. I have no idea whether this could be seen as violating copyright.