Hello Denilyn. Yes, The ET-8550 can print on 12" x 12" paper as it supports sizes ranging from 2.2" x 3.4" to 13" x 78.7". The thickest paper we have tested on the machine is Epson Premium Photo Glossy, which weighs 79 lb. For cardstock, we have tested similar Epson paper that weighs around 44 lb. Please be aware that these recommendations are for Epson paper only. You can try a cardstock that falls in that range, but your results can vary when using other brands and heavier paper. Regards, Kevin - The Epson Team