This is something I slapped together on AutoDesk 123D Design to mimic the atomic bomb used by Baby Groot in the preview to Guardians of the Galaxy 2. I printed it out of Wood PLA, since that is what I had in the printer at the time, after I had just printed a Baby Groot. There is a small overhang on one side that may need support, but it is not bad. A little paint and some imagination and you're off. This is not a photo realistic model, but gives a general idea.