If you can't have a brain in a jar, the next best thing may be a knitted brain in a frame. The beauty above is handmade by Emily of aKNITomy and available for sale at the Boing Boing Bazaar in the Makers Market. From the product page:
These brains are hand knit in a wonderful 100% Peruvian wool, and then stitched into place atop a pad of felted wool roving (this gives them a 3D quality).
The brain is sewn into place on top of a lovely hand knit background made from merino wool and kid mohair. Gorgeous.
The piece is framed in a dark stained wood frame that measures 5″ × 7″