This is my first post so bear with me, but I have a job at a local fast food place, I have made a great little way of passing my breaks by in my car. I grab a large cup and a water bottle (drinks are free) and I make a grav out of it, and I keep it in my cupholder through my breaks and keep the same cap. Hope this helps out somebody willing to try it and please post with some feedback
You could use tin foil but I use a socket top like the metal tool bowl it fits into a smart water cap perfectly
having a grav bong in your car's cup holder is sick i use those on college campus' when we can't smoke in dorms and shit like that. just keep an eye out for piggies
also i make grav bowls by melting a hole through the top of a bottle cap (preferably coke brand) and screw off the mouthpiece from a metal bowl and shove it through the top of the cap while it's still melted. really easy to make and gets you frosted
this is what i use for a grav 1.) 2 litter bottle ( best is a 2 litter ) + cap from the 2 litter < do not throw this out 2.) a JUICE / OJ CARTON 3.) SOCKET take the 2 litter bottle cut the bottom off just where it starts to curve a bit. take your JUICE/OJ carton cut the top off where it starts to /\ <-- cut the bottom i most the time open the top up and then cut a line down 1 side of the carton | | like that and then _ cut it off and go around. take the 2 litter and stick it in the carton make sure it fits all good and moves around up and down fill the carton with water. you will need to get the socket and the cap from the 2 litter take a knife and make a hole in the cap and dig a O out not to big and not to small just middle make sure you make the hole right in the middle of the cap. turns out better that way and will last alot longer. once you get a good size hole take the socket and jam it in the top of the cap i put a glove on and use my hand cap side in my hand pushing the socket in as the socket is on something standing up. once that is all done you can pack a socket up I been rocking a grav for 15 years oh the days of a gravatron i say that a 2 litter is the best it is 1 because it fits in the carton with out a problem. 3 litters are hard to find something that fits (laying around the house that is) the 2 litter cap works the best overall u can have it in your pocket and bring it to peoples houses that have gravs set up already 1 cap does wonders. do not forget to change the water from time to time also do not forget the carton is made out of paper and water breaks paper down after time so do your self a favor and replace the carton every few weeks to a month tops. u dont want grav water all over the floor. its nasty and way more stinky then bong water