Any good non name brand isulators out there?

[Lypho]

Hello im doing a school project and i need some sugestions. For the project i hafto insulate a 2L POP bottle. The rules are
1:there must be nothing outside the bottle
2:The bottle MUST contain 550ml
3:NO commercial insulators

With those rules here's what i currently foght tin foil suranerap water candelle wax grass electrique tap thx for the help
Lyph

 

[Lypho]

pls help

 

[Dexter Sinister]

Plain old dry dirt's not a bad insulator. Try this: get a few centimetres of dirt into the bottom of the bottle, then thread a balloon down into the bottle, without dropping it, pour 550 ml of water into the balloon, then hold its open end to the side of the bottle neck and pour more dirt in around it until the bottle's full. Then stretch the neck of the balloon over the mouth of the bottle, and you've got a bottle full of insulating dirt with a 550 ml cavity inside. If the balloon proves to be too rigid, you might try a condom.

 

[Lypho]

Plain old dry dirt's not a bad insulator. Try this: get a few centimetres of dirt into the bottom of the bottle, then thread a balloon down into the bottle, without dropping it, pour 550 ml of water into the balloon, then hold its open end to the side of the bottle neck and pour more dirt in around it until the bottle's full. Then stretch the neck of the balloon over the mouth of the bottle, and you've got a bottle full of insulating dirt with a 550 ml cavity inside. If the balloon proves to be too rigid, you might try a condom.

Ya... about that my teacher says that he's gonna drink the contents in the end and is it easy to keep all the dirt in a wet dirty state?

PS:good idea just not practicle for me.