My son and his friend requested a Minecraft Wither , with the ability to move all three heads. I wanted it a nice size - not too big, not too small. However with printed pins, it limits the minimum size of a model as I’ve found small printed pins tend to wear over the long term. In the end, I decided to try using LEGO Technic pins , which my son has a LOT of sitting in his LEGO assembly cabinet. If you need a bunch, you can find them on Amazon or Ebay for $10 for ~300 pins.
All in all, this assembly method turned out VERY well. I’ve printed two of these Withers on my i3 and they fit together nicely. The pins snap in solidly and they hold the parts just about as well as in normal LEGO bricks.
Download and print: http://www.thingiverse.com/thing:324199
Let me know how well it fits!