A part from my protection Helmet, that I use for lawn mawing with a line Trimmer, got broken and for fun I decided to print it (even though you can buy a whole Helmet for under 10 $)
Its an adjustable "geared band" (or whatever its called) used to tighten or loosen up the helmet with a help of a knob.
There are so many different variations of helmets, that it probbably wont fit yours. This particular band is RIGHT side with "upper" gears, there's also left one that has gears from "down" side (didn't make it because it wasn't broken). After printing you can bend it using the edge of your filament spool. I did it old fashion way: eyeballed it using a lighter.
Its just an example of what you can do with your 3d printer.
SketchUp Make 2017
Step 1: Broken Original Part
Actual part that got broken
Step 2: Tools:
All measurements, needed for 3D model, were done by using digital (absolute) caliper on original part.
And programm called SketchUp Make 2017.
Step 3: 3D Model Using SketchUp
Using basic tools like rectangular shape, circle shape, and extrude command in programm called "SketchUp Make" the basic shape was made (pic.3).
A little bit tricky (for me as a newb in 3d modeling) was to do geared teeths.
Long story short I made one "sine wave" and rest was copy-paste (pic. 4)
3D model is 1:1 with the original part, and it was printed without scaling it.
It holds very well (in fact it holds fantastic) and it did not brake, bent or got loose.
Step 4: Finished Part
Assembled part after printing.
After printing it has to be bented.
This particular "part" was bented using "eye-ball it" method and a lighter.
Second, more profine way would be, heating it in the oven at 50°C for a minute or less, or on preheated 3d printer bed (60°C-70°C with an alu foil betweek glass bed and printed part to prevent sticking it to bed itself) and using the edge from fillament reel to bent it.