that looks pretty sweet! what sort of plastic are you using, and how are you gluing, adhereing, etc?
I get the 1/8" ABS plastic in 4 x 8 sheets from a local company called Regal plastics . cost is around $40. I put it together using Methyl Ethyl Ketone, or MEK for short. It is a solvent normally used in painting (I think) but it melts the ABS quite readily. I also make a paste glue using the MEK and ABS scraps that is used for sealing the joints.
Weight as shown: 22 LBS. hoping to stay right around 25 LBS RTR, which will be about 10 LBS lighter than my last one. It may be heavy...but it's almost bullet proof.