what thickness sintra should I use

I found a supplier in my town that sells expanded pvc sheet for $18 for 2mm or $22 for 3mm. Which is the ideal thickness to use for troopable armor?

Myself and the local group tend to use either 3mm or 6mm depending on the project.

3mm should do you just fine.

I would have to agree with thaxos.. 3mm will work just fine (have have made a couple sets of armor from 3mm).. with a single 4'x8' sheet you will have more then enough for your armor and possibly a second set of armor as well.. One piece of advice though for the gauntlets and helmet ( if your gonna make them as well) use 1mm as it is easier to get to form for a tighter curve