A pushbutton action that advance between the poles would be even better than a slide.
See
@Fish4Fun post #6 above. Tell us what you are trying to DO and let us make suggestions on how to do it. A Microchip PIC microprocessor can easily be interfaced to a push-button switch to increment a software "counter" that selects one of several PIC outputs. Each output controls at least one relay coil, so it can be as simple as a relay with a SPST normally-open contact, or a relay with multiple poles and multiple throws at your pleasure, with either more contacts on the relay or more relays at each output, whichever seems more practical for your application.
You can also do this with discrete logic circuits but PICs are much less expensive, even if you need to use several PICs to obtain enough output port bits. Don't get carried away and think you need a fancy PIC with lots of output bits when two, three, or more PICs with just a few bits on each PIC will do the job. It all depends on how long a "slide switch" with how many poles you want to make. Multiple PICs will of course require some housekeeping program logic to keep them all "in sync" and working together. It would also be advisable that they all execute the same program, so the PICs would be interchangeable. This would make the circuit much easier to test and debug.
If you need a mechanical solution, mount a micro-switch on a slide between two rails with adjustable friction, perhaps by varying the spacing between the rails. A series of "bumps" or detents located outside one rail would actuate and de-actuate the micro-switch as it moved (slid) between the rails. The rails and the detent strip can be "printed" easily on a 3D printer. Use the micro-switch to increment the software counter in one or more PICs. Or de-bounce it and increment a decoded hardware CMOS or TTL counter, the decoded outputs controlling relays as previously described.
For what application do you need this switch? Do you need more than one switch? I am visualizing some sort of audio mixing board with dozens or hundreds of slide switches. How about some hints on what you are trying to DO!
