ATF cites molotov cocktails in their examples of Destructive Devices, so....
...could I build a molotov cocktail on a Form 1?

Or would ATF declare me persona non grata and never approve another Form 4 for me again?

Model:  Sam Adams Boston Lager
Caliber: 12 fl. oz.
Overall Length: 9"

I'm thinking it would look nice to frame the approved form in an 8.5x11x3 walnut shadow box with the serial-number-engraved beer bottle next to the NFA tax stamp.

Sounds good to me if you have $200 you want to part with.  Might want to go bigger than a beer bottle though.

Use something classy.... 40oz of Old E or Colt 45.

Like

How are molotov cocktails DD's and flame throwers aren't?

I don't know why one's NFA and the other isn't.  I don't make the rules, I just follow them.  

So, nobody can recall this topic ever coming up before?  Since nobody is telling me, "you idiot, don't do it," I guess I'm one step closer to pissing away $200, plus the material costs for the display case.

I thought about using a vodka bottle, but that'd make the display case a little bigger than I planned.  Then again, with the larger case, I could even fasten a small hammer to the side, and the words "In Case of Emergency, Break Glass".  Since I'd be the only one authorized to use the device, writing instructions to myself seems a little silly; though, I suppose the written instructions could be more useful as I get older and more forgetful.

I don't know if this is the voice of reason or not, but I have a suggestion.
If you're going to pay $200 for a tax stamp on a novelty item, MAKE IT ONE YOU CAN USE.
Here's a thought. Have a metal ring machined that will thread onto a bottle, like a bottle cap but open on the top.
Have your serial number engraved on that ring, rather than on a bottle itself, then the ring is your registered DD rather than the glass bottle.
You can then use the Molotov Cocktail as many times as you want, just retrieve the ring each time and use a new bottle.

Brilliant!  Like engraving the spoon on a live grenade!

If you're going to do it then do it right and use an original bottle made for the purpose. These bottles are original Soviet molotov cocktails with label explaining how to use them. Member SVDS (not sure what his screen name is here) had them a couple of years ago and he might still, he's on theakforum.net.

motorcityman, that's really cool, but could that possibly run afoul of some "firearm importation" regulations?  Sort of like imported non-sporting shotguns?  

I'll try to look up SVDS.

The problem with the authentic bottles is that their non-standard sizes would prevent me from going the route of using a serialized metal ring, if that is even a viable option wrt ATF rules.

Tag and ive always assumed it is gasoline that is the liquid ?

The combustible is sort of irrelevant in my case, as I'm just trying to make a display piece.  I can't find any active listings for authentic bottles, though.

I'm also partial to the smaller bottles because I'd find some comfort in knowing that I'd be able to actually toss the thing.  I have a steel plate in my arm that inhibits full range of motion.  Rockclimbing is no problem; throwing a baseball, however, will bring me to my knees in tears.  Throwing a grenade is a slightly different motion, but still quite painful for me.  So, I'm thinking about buying an M203 next year with the funds from my HSA...you know, as a medical aid ;-)

See if you can machine a heavy duty metal cap for a bottle and register just the metal cap as a DD. That way you can have infinite fire bombs, just make sure you find your cap after you throw it