Update Note: I found a few better parts at the Depot last night that eliminate metal on metal contact and increase the extension range. The price goes to $9.43 mostly because the longer threaded rod is more expensive. Changes to the process are noted in bold
Strobist is having a week of Home Depot based postings. The photo studio compression pole is my contribution.
This device uses light spring pressure to hold a pole between your ceiling and the floor. This pole can hold up a backdrop or be used to mount other lightweight devices like flashes and reflectors.
To move the pole you simply push down and the tip comes away from the ceiling allowing you to reposition the pole.
This version is only adjustable within about a 2 inch range. If you need a different length you'll need another $1.79 length of metal electrical conduit (EMT).
The parts to build one cost me $11.24 but that leaves lots of parts for more. The unit cost is $6.86 each.
Here is a video of the compression pole in use.
Step 1: The parts
Galvanized electrical conduit 1/2 inch X 10ft (EMT)
Compression springs package 16084
1/2 X 12" threaded rod
1/2" EMT Bushings
1/2" wing nut
1/2" SAE washers
3/4" rubber leg tips
A few feet of Permacel or duct tape
A few feet of parachute cord
The updated version uses a 1/2 X 24" rod, a pair of "1/2 Adapter SxMPT" (item 436-005) and does not use the EMT bushings
There are a number of different spring packages at the Depot. I used the one marked 16084 in the lower left corner of the package.