i think this is the correct question to ask. did you just create ~/.local/bin folder? you can look at the end of ~/.profile that this will only be added to $PATH if the folder exists.

the easiest way is to log out and log in (no restart necessary!)

otherwise you can also execute source ~/.profile and then yt-dlp should be available.

the chmod +x tip from the other comments could also be necessary!

how do you vibrate? do you try to vibrate your whole mold? like using a “concrete vibrating table”?

maybe you can build you a equivalent of a “handheld concrete vibrator” in even smaller, and just put it into the concrete?