Alright, please define what you are calling a contact explosive. 

Second, where are you getting this thermite? 

Third, why would you even need to use something that vibrates, that is waaaaaay too sketchy and unlikely to work. Why not just use an electrical current to like

a fucking lightbulb.

Also how is he going to make this contact explosive
what is it made out of?
is it tatp?
because that shit is sketch. but also the most likely home made explosive he would be making.

also why the fuck do you need a bullet in that scenario. That makes no sense.

in

what

way

would you

"pull the trigger"

:^)