if you want it to actually be random,

[sick bay]

can you please explain this futher. what's selector? hooked by circuit network?

[sly ore]

the selector combinator, it has a mode that chooses a random signal
you'll need a constant combinator wired to the selector combinator
selector combinator wired to an arithmetic combinator
arithmetic combinator wired to the train station

[sick bay]

thank you I'll try

[sly ore]

constant combinator with constants of different values, ie spooky ghosty(5),iron plate(15),wooden chest(6)

between 1-255 i think