This has probably been discovered before, however if you use a similar technique to teleporting Sentries you can remove the gadget that a sentry holds! Here is how to do it:
Put down a sentry, zone, and a item granter
Connect a wire from the zone to the item granter
Make the item granter remove 1 of the item the sentry is holding
Yeah, I can’t exactly think of anything interesting you could do with it off the top of my head, however it should be able to at least help with the look of passive Sentries for NPC characters and stuff.