Head attaches to body with a pen spring with min. inner diameter 3.2mm, max outer diameter 6.2mm, and length about 29mm. Add a pebble or two or whatever else you can find into the head as it prints for the rattle effect. Not too many, or it'll depress the spring and make its head sag. :(

Base is the same, except with 1mm cut off the bottom to reduce overhangs.