The Minecraft (tm) theme seemed like a good one to start with when looking for fun things to print.
The short storyI created a model of a TNT block which my printer could handle (see longer story below to see why) - printed it - and posted it on Thingiverse as "TNT Block". It has 84 downloads in 10 days - so not too bad.
The longer storyI first found a TNT block on Thingiverse created by someone else and it looked really cool.
|FAILED print - stopped part way.|
Notice the strands which fell.
The TNT labels on the side of this model I found were definitely not friendly to my printer - and as soon as the TNT labels on the 4 sides started to print, the problem was clear - the extrusion was falling off the sides rather than sticking to the model, because there was nothing under it to hold it up.
So - in my model - I created a subtle slant to every overhand - so it still stuck out the side, but with enough of a gradual slant to support the material as it was extruded.
Summary - it takes some time to create a model which will print on an FDM printer and some problem solving during the modeling process to get the results you want.