Umm I just got an email to post something funny so here goes.. LOL
How about a butt plug with a Stargate base so it loos like you got a gateway to the unknown.. it could be battery powered and vibrate, but have some kind of jell-like inside the stargate doorway part that jiggles with the vibrations!! lol
the energy wave thing that pushes out on activation could be the plug part that you insert. could be bumpy or smooth dunno but you could display it for sure..
The mechanics could be you "dial the gate for your destination(vibe settings)" then push the jelly part to activate a push on switch behind the event horizon.
you could use the metal contact connection to charge it and have a little ramp like charging station modeled like star gate command
IT WOULD BE OUT OD THIS WORLD... LOL
bonus part about it having 7 symbols is you could have 7 options OR you could be really nerdy and you actually have like combos for settings like 7 symbols to make 1 setting like a combination lock or something.