Personally i think it's a good thing to immerse yourself into your robot kink without advertising it to the world.
The good thing about a custom temporary tattoo is that you can buy a batch of lets just say, a logo you made, and use it roleplay purposses.
And after it you just rub it off.
And permanent blacklight tatoos are great in the long run, nobody can see them except when you use a blacklight.
I can easely see someone use this to have seams, logos, id numbers, or warning labels tattood on them.
And after 8 years they slowly start to fade away, so long long term there is no true downside.
There are also glow in the dark tattoos but i would advise against that because:
1) they allways would glow in the dark and it would advertise what you would be into everytime it gets dark
2) most glow in the dark tattoo ink has phosphorus in it, which is, well, verry toxic.
Thoughts anyone?