Originally made a crochet Lady Cassandra using coat hanger wire.  It was neither square nor even, was difficult to work with and left sharp pointy bits.  Then I got a 3D printer and I knew what I had to do!

100mm wide, 150mm tall.  The two pieces have a gentle press fit.  Illustration is white PLA on an Ender 3.

Crochet instructions: Make a rectangle with SC so you have about 15mm clearance inside the frame.  Go around the edges (SL,SC,DC,TC,DC,SC,SL), repeat as needed.  Loop a piece of yarn in/out through the outer stitches, looping around the frame at the TCs.  Weave in ends.  Embroider the eyes and lips.  Present to your favourite Whovians for squeals of delight.

The character is copyright to the makers of Dr Who so I wouldn't go making these commercially.  Do what you like with the STL though.