LOL! OK, ;-)

Delrin rod, Acrylic pipe/rod, PVC plumbing (not to be used for VHF), is
key to the project.

There are many pubs out there on making variable capacitors, the ARRL
Radio Amateur's Handbook, and lots on the net. This is important, because
the body is basically the same - rods, two square blocks of plexi or
other insulator material, feed through hardware.

The difference though, is you can use three threaded rods, but one must
be smooth. Use a 1/8" brass hobby rod, threaded at the ends. You'll need
a die & handle for that.

Wind your rod. 14AWG house wiring is what I used. wind a spiral with one
end ending in a near-complete circle. This will be the "common"
connection.

Your slider. Use a nylon bushing. This will be needed for friction.
Electrical will be less important, because there will be no potential
difference. Make a brass tab and dremel a notch in one end that'll fit
the diameter of the wire used. The end of the tab should be bent back on
itself a bit, to reduce binding. The other end of the tab, drill a small
hole and attach to the nylon bushing with a 2-56 screw. Solder a flexible
wire, litz, or that stuff used on speaker cones, from the tab to the end
of the slider rod.

Your common. Same tab, only soldered directly to one of the other,
probably threaded rods. The tab will touch the end of the roller you made
the complete circle of wire.

Assembly. Same hardware for making a varicap, only instead of where the
plates go, place your roller.

I should really make a drawing ;-)

--
Gregg t3h g33k
"Ratings are for transistors....tubes have guidelines"
http://geek.scorpiorising.ca