Your shop light needs to have a keyhole slot for these to work as mine are shown. 

My lights came with little wires and hooks to hold up the shop lights, and since they're a fixed length, this meant that I couldn't install them as well as I'd like.  They hung about half an inch below the level of the ceiling joists, which allowed them to swing and move if they, or the cord, were contacted.  I looked around, and didn't see anything that fit how I wanted to mount the lights, so I whipped this bracket up.

This bracket allows me to mount the light up into the joist space where it's sheltered from contact, but still allows the light to fully shine into the room.  If your joists are 16"o.c. this bracket will hold the light almost perfectly centered in the opening.  I recommend testing the placement by holding the light up in place to determine where and how you want to mount them

There may be some heat put out by your lights, so I don't recommend PLA.  The yellow bracket I show was printed with HT-PLA, and that's been holding up just fine.  I recommend installing these following the method I found to work best for me:

1. Insert a screw into the hole at the end of the long arm.  

2. Test the fit into the keyhole.  You want it snug, not tight - easy to slide in, but it holds

3. Insert a screw into the lower side mounting hole

4. Hold the light in the position you've chosen, and run the lower mounting screw in - do NOT tighten it fully at this point

5. Remove the light from the bracket and set it aside

6. Position the bracket in a plumb position (straight up and down) and run a screw into the upper mounting hole

7. Tighten both mounting screws so that the bracket doesn't move.  This side is done

8. Follow steps 1-3 with another bracket

9. Raise the light into position, and mount it, using the installed bracket - use that keyhole fitting and the screw to hold up that side while you get the other side positioned and mounted

10. Holding the unmounted bracket in place, run the lower mounting screw in, again, NOT fully tight, just snug enough to hold it in place.

11. Remove the light again, and set it aside

12. Install the upper mounting screw and tighten down both mounting screws

13. Install the light using both screws in the brackets, using the keyhole slots on the light

14. Plug it in and deal with the excess cord in some fashion (zip ties, velcro etc)

Hope you like it - enjoy!