Here is an adjustable wrench I made a while ago in blender, after seeing Enginerds Adjustable Wrench Challenge. I used tbusers files as a base, modifying it to have a square channel for easier printing. Once printed out it works well on loose things, but on tight things the plastic isn't strong enough.

I have modified the Wrench_Arm part to print upside-down, removing the need to use support material, however I have left the Wrench_Arm STL file as the modified version (Wrench_Arm_No_support) requires good bridging settings (Something that I am having trouble with myself), although this is mainly cosmetic

You will need to print out the Wrench_Arm, Thread_Center_Hole and Wrench_Arm_No_Support STL files. If the Wrench_Arm_No_Support STL wont fit on your build platform, you can also download the two halfs as separate file (Wrench_Arm_1_No_Support and Wrench_Arm_1_No_Support) Depending on your printer you may need to use a drill bit to enlarge/clean out the alignment holes in order to fit a filament peg in.

To assemble the wrench:

1. Glue the two clamp arm halfs together using short pieces of 3mm filament and superglue.

2. Glue the two threaded part halfs together around a piece of 3mm filament, leaving a few millimetres sticking out either side. This will act as an axle for the threaded part to rotate around

3. Test fit the clamp arm and threaded part in between the wrench arms, holding them together with tape, to make sure the clamp arm slides properly. If the two wrench arms don't fit together with no gap, sand the top of each part smooth until they do.

4. Glue the two wrench arm halfs together around the threaded part

5. Slide the clamp arm in to the wrench, turning the threaded part to draw it in