I'm looking for schematics or a quick solution to make a unit that will allow me to apply 12 VDC to a device and have it alternate 12VDC between two contacts. Essentially making a wig wag setup.

how long do you want it to stay each way?

Two DPDT relays and an RC network to slow it down. I rigged two relays up once without an RC network and they made quite a racket.

how long do you want it to stay each way?

About 1 second on each side.