This is just an enlarged, segmented version of the excellent sea turtle by Simonarri.
I segmented into 9 parts so as to print as large as possible on my 20cm x 20cm bed. It prints cleanly without infill, without supports, without raft, and without brim. I used 3 shells (1.2mm total) for strength. Glued together with model airplane glue and painted with spray enamel and acrylics.