If you want to duplicate a "Real" par bar...
I am making a couple now, here are links to what you need:
> Aluminum pipe, 2" OD 0.125 thickness T6061 minimum, Im using 90" length for 6 pars , or 5' for 4 par ACL bar
http://www.onlinemetals.com/merchant.cfm?pid=4369&step=4 &showunits=inches&id=71&top_cat=0
> Aluminum box to be welded onto the end with your choice of power-in
http://search.digikey.com/scripts/DkSearch/dksus.dll?lang=en &site=US&WT.z_homepage_link=hp_go_button&KeyWord s=377-1191-ND
> Wire strain relief
http://www.grainger.com/Grainger/HUBBELL-WIRING-DEVICEKELLEM S-Cord-Connector-2DPE4?Pid=search
my directions:
>drill a hole into the end of the gang box (big enough for your wires to fit through once welded to pipe)
>take it to a welding shop, (or if you can mig/tig aluminum) have the gang box welded to the aluminum pipe
>drill holes for wire inside pipe and run it to the gang box
>put strain reliefs on around cord and screw it into the tube (you can either tap the hole so its nicely threaded, or just drill it wider and put it through and seal with silicone)
> wire ends to input connector( in my case, a 19 pin socapex connector, but you can use powercon or a nema twist for single circuit or your multipin choice)
>wire bar ends to either lamp sockets or to edison or twist receptacles
I can make these for any type of conventional light, at any length, and I am thinking about making some for LEDs that have integrated DMX, so you plug both your powercon and DMX next to each other and then power and dmx is fed out along the bar.
just google thomas truss, par bar, or any other combo and you can get examples of what this would look like.