on line dealer, then they will (should) always state the composition of the body. 2) Some brands, such as Cult Scale, BoS, Laudoracing, KK-scale, GT Spirit, BBR, Top Marques, Tecnomodel, and Otto are virtually all resin versions. 3) If you're looking on Ebay, if they don't state the composition then look for other listings of the same model and check the descriptions there. 4) Finally, if that doesn't work, and especially for older models, suggest you go to the website carmodel.com (German dealer), choose the English text, put in the description by name in the top box where it states "search", then choose the scale, and choose "all types" in the box below the scale choice, and check the box listed as "Encylopedia"; that will not only show their stock of current models but also a huge number of models which are no longer available due to being sold out or no longer being produced).

BTW - the resins they use today don't warp.

Good hunting!