I think I last saw one in 1989, but (IIRC) old Army canvas tents (GP Medium and/or GP Large) used 2'-long sheetmetal sleeves to connect 3"-dia wooden poles.
For my first try at a Tipi, I cut my 12' shelter out of a 15x20 painter's tarp. (I don't use a larger tipi nor liner, as they are too "modern" for my taste.) A 12' has enough room for myself and both pre-teen sons; or me and a dog and a couple footlockers of campcraft supplies. It isn't a well established tipi, but it is a start.
I tried eight pairs of 8' 2x2s tied with round lashing. Because I wasn't doing actual woodwork, I didn't mind the local Home Despot shelving the most dogged-looking 2x2s in the civilized world. I used sisal twine for the lashings, and the whole thing came down in the middle of the night.
My second attempt was six 18' 2x8s ripped diagonally; a dozen poles, each 2x2 at top and 2x6 at bottom. I cargo-strap them over my Honda Pilot's luggage rack and tie the ends to the bumpers. Those poles have been set up a dozen times, and work pretty well.
If I can learn how to post images, I'll throw a few night-time pics of our Huskies silhouetted by a romantic fire-lit Tipi. (if not, just imagine it.. the scene probably looks better that way.)
Stu