Simple sand shovel I designed for my daughter. Prints great with no support and has no overhangs.
I printed mine up on my Ultimaker2 using 2 shells (0.8mm) and 0.1mm layer thickness (why not?) in PLA, with 15% infill. It took forever (about 13 hours) but it looks great. 3 shells would make it stronger and possibly less porous but it seems fairly sturdy as I printed it. It hasn't been punished by my 2-year-old yet but it has fairly chunky wall thickness and everything is smoothed so there aren't any bad stress points (especially on the handle).
I've included the Blender file I used to create this. You might want to shorten it, the scoop is fairly tall.
I wouldn't go leaving it to sit in a hot car if it's made from PLA. I wouldn't go trying to break up hard dirt or anything either. I'm not sure how well it will do with water either, I expect the porosity will largely depend on your printer and settings.