Well, Hello there!
Do you recall my earlier post about attempting one of these?
I never did find some cool knit fabric (anyone know of a good online resource?) so I used one of Scott's old cast off shirts to give this a go.
I also stated in said earlier post that some 'ghetto sewing' was in my future. It's all I do. I am a master at ghetto. So pick up your scissors and let's begin.
You can do this with a regular T. The shirt I used here was a polo style.
I used a rotary cutter, ruler and mat. This saves loads of tedious cutting time and keeps your fabric nice and straight but you can do it with regular fabric scissors.
Start by removing the side seams, sleeves and neck trim. Trim close yielding you the biggest piece of fabric you can.

Place those pieces of fabric right sides together and sew the bottom flat edge. Don't have a serger? Neither do I! Find a simple overlocking stitch for knits on your machine. Most have them (T's don't shred much anyway so you could even use a simple knit stitch for stretchy fabric).

Oops- I forgot to even up the shoulders and make them straight (See? Even in ghetto sewing I am a good and wise teacher and include my lame mistakes).

Ruler across the top and swipe! Off with the shoulders and made a straight edge. I didn't go all the way down to the placket. Keep reading to see why.

NOW I have a flat edge on the other end and can sew that together. If you were to lift this up, it should be a 'tube' of continuous fabric with the right sides facing in. Check.
*TIP* I could have cut to the bottom of the placket but I wanted as much length as possible and since we are cutting this into strips anyway, I could get away with this small section of missing fabric. You will see what I mean in a minute....

Now, make sure your 'tube' is completely flat, no folds or wrinkles. One of the seams will remain in tact, the other we will cut through. Lay the seam you are NOT cutting through at the top and begin to cut, one inch apart, from the bottom edge to the top, stopping two inches from the end.

Only that remaining seam will be the spine holding all your strips together.
Now you need to stretch out each loop to encourage the fabric to curl inward. You can do this on the table top but it gets a little tangled after a while so I slid it on my arm, seam on top, and pulled each one down this way.

The strips didn't curl as well where the other seam is. Hence the benefit of using a yard of fabric over a T. But it still works quite well, I say. Maybe after a washing it will help.
Now lay the seam flat and roll it up like a sleeping bag.

Then use a patch from one of your discarded sleeves and sew it around your seam with a quick whip stitch.

Tada! You have enough to double this up around your neck if you want.
I am excited to try some others now. Think of how cool this could look with old concert or vintage t's and even different colored scraps around the spine roll at the end. Are you inspired?! Good. Mission accomplished. Enjoy!