Help with TK limitation

[Not another shrubbery]

Originally Posted by DangerousThing

I'm going to be gm'ing a game that uses GURPS Psionics, and I'm thinking of a limitation on telekinesis.

Imagine that the character can only use their TK on a set of six specific 2" steel balls (perhaps with some "decorations" al la the Phantasm movies). The character could make more between adventures, but with this TK, they could only use the set the character has with them at the time.

I'm thinking perhaps a 50-60% limitation? Does this sound right?

The 'six steel balls' part sounds quite restricted. What do you envision being able to do with them?