I like making skinnies in 6-8’ lenghts out of 2x4s, since then they can double as somewhat wiggly gapping bars. I used to have a pair–a 5’ and an 8’ skinny, both 2x4s. The 5’ was the primary gapping bar, but the 8’ helped.
Here’s the tools I would use to assemble 2x4 skinnies:
Miter box (even the cheap plastic ones, so long as you can get the 2x4 into it)
Shark tooth saw (what’s the real name? They only have one handle and often have a picture of a shark on the blade guard they come with). well, any wood hand saw will work. Don’t worry about time, I find I can get through a 2x4 in as little as 45 sec.
hammer
nails, not framing (use nails with heads)
Screws
Screw gun or power drill. I use a milwaulkee hole shooter, a bit overkill
Screw driving bit
Drill bit that’s about 1/32" smaller than the bottoms of the threads of the screws
Screws (use phillips head c-sinking, they’re the best. Self tapping or sheet metal, you know what i mean.)
In my gallery are some videos os me using the rails, which will show the basic construction of them. I made then 7" off the ground, and to save wood did a 45 degree miter cut at the ends of stabilizng legs. That cut saved 3.5" of wood for every cut made. Also makes the obstacles a bit more dangerous. If you make the rails so that the legs don’t extend beyond the end of the rail you can put them end to end.
You only need one supporting leg (the flat thing that keeps the rails from tipping. It’s like the top of the T) in my experience, on rails ~8’ and shorter. This is helpful since then one end is compact and can sit ontop of posts, etc. It also makes it easier to setup and makes for cool lines, like leaning the leg making the top of the “T” on stairs and propping the other end on the ground. You can then adjust the angle of the DH skinny. The supporting leg can also be a 2x4, and it needn’t be longer than about 26". My old ones had a 3’ and a 2.5 support, both of which were overkill but useful, sometimes.