If I were doing this, I'd emulate a 7 segment display. Think of an 8 - there are 7 segments to it. 0-9 can be expressed as a set of 2 or more illuminated segments. You can use a relay or TRIAC to control each segment.
It isn't clear how you intend the user to control this so it's hard for me to know what to suggest. A crude solution is to use a 10 position, 7 pole rotary switch but that's going to get expensive, if you can find them. A more sophisticated approach is to use a 10 position BCD encoded switch with a BCD to 7 segment decoder. This will output a signal for each segment. You can use this to drive a transistor to control the relays or TRIACs.