I have only briefly looked but I'm struggling to find a supplier of 150gsm CSM, i can only seem to find 100gsm at the closest. Also do you think 2x 850/900gsm would be fine in place of 4x 450gsm? ( I have quite a bit lying around). I understand the exotherm issue but I'm guessing the 900gsm should be fine other than taking a little longer to manipulate around corners. (darn iPad kept auto correcting "exotherm" to "exit germ"!!:O)