Cookie Tin Tailpiece ideas. Pressure or tension on tin can

Ok so I made a few cookie tin 3 string guitars. I used a neck thru design as Im not sure about the almost neck thru design yet. Im just beginning to grasp some fundamentals with some great help here.

here's 2 more questions please!!

1) I am using a pic hanger with 3 holes to hold strings on the tail piece and eye-bolts as tuners. The pic hangers are costly and I'm trying to come up with a solution for a cheap method. I did see a bottle cap as a tail piece. My question is what kind of drill bit do i need to drill through metal or tin? any special type? I am considering some brass pipe I had laying around or finding some thin metal?

Still seems to me the lack of wood in the almost or halfway through the guitar design guitar without the wood to rely on on the tail piece design is a bit perplexing regarding tension on the can. The idea being that I don't want to put pressure on the tin can itself as the string get tensioned. This is all fine with a neck thru design because I attach the strings to the wood neck via the pic hanger... but I'd like to try a neck halfway thru the can and or come up with an inexpensive solution for both designs as far as a tail piece method and material. What shall I attach the strings to? This goes for neck through and the (untried) halfway through cookie tin guitar as Im out of money for more pic hangers like the one in my pic here. im not ready for a bolted neck type or "real neck" yet.

2) Bolts for NUT and BRIDGE. I like the idea. I am currently using some driftwood. Nice tone. i'd like to try bolts because I have some already. As far as the nut I see how the head of the bolt can reside off the neck. As far as the bridge i don't understand how the bolt head on the bridge wont cut into or dent the tin can? I'd like to hear how you do it. I was thinking of cutting the head off the bolt but I only have a small hack saw and it seems pretty difficult. I did it once a long time ago with a very small screw but these bolts are much larger. How do you cut off the head of the bolts for the bridge or keep it from denting, make the bridge bolt even etc? Special method or saw to cut the heads off?

THANK YOU!!