I've just started playing with sprang, and I wanted to experiment with various techniques without trying to produce a historically-accurate item. The result: a stripey, lacey bag for my favourite child.
Frame
I lashed together four pieces of broom-stick with kitchen twine. It's not perfectly stable, but it works.
Then I tied two long double-pointed knitting needles to the upper and lower edge of the frame, leaving room for me to pass the balls of thread between when I wrapped the warp. There are a few extra bits of kitchen twine here and there keeping things steady, and another acting as a safety-thread (securing the previous row of sprang while I work the next).
Thread
This is made out of crochet cotton in pink, purple and blue (colours chosen by the recipient of the bag, who is nearly five).
There are 32 warp threads in each colour: 16 at the front and 16 at the bag. For the third or so of the bag I used the threads in groups of two - treated it as 8 threads front and back in each colour, with each thread being made of two elements. About a third of the way through, I swapped to single threads (which is why the bag gets a bit wider part way down).
The crochet cotton was easy to work with: strong, slippery, and not very stretchy.
Patterns
I made it up as I went along, to no particular scheme.
The whole piece is worked with a Z-twist (which gives a Z-twist in the entire top half / front of the bag, and an S-twist in the back).
I experimented with double and single threads, pairs twisted together for extended periods, and lace patterns made with holes.
I worked most of it with my fingers, with occasional help from a crochet hook and some knitting needles - especially useful near the centre, where there's little room to get fingers in.
Progress photos
Sprang on the frame
The work in progress, on my bodged-up frame. I worked most of it with the frame nearly vertical, sitting on my knees and leaning against a table.
In this second photo the last rows of sprang are in place. I didn't realise how much thread the chain that joins the sides would take up - I could probably have stopped a couple of rows earlier.
Off the frame
Here it is with the tension off, but still attached to the rods top and bottom. As you can see, it narrows a great deal if you let it. The centre - the gap between the top and bottom halves - has to be secured, or the sprang can unravel. I've used a sort of chain stitch to loop each thread through the one next to it, as was done in many medieval Scandinavian examples; a cord through the gap will do the same job.
And here it is entirely off the frame. As the twist all goes the same way it wants to curl into a ball. So much for the lacy patterns! Blocking required.
Blocking
Here it's been washed in warm, soapy water, rinsed, and pinned - well stretched - onto a padded board to dry. The process is a bit fiddly.
After it's dried and unpinned it looks like lace again. The wobbly edge is mostly because I changed from using paired threads to using single threads part way down.
The finished bag
I sewed up the sides with the left-over cord from securing the centre, and tucked the ends away. The draw-string and handles are made from cord plaited out of bundles of the same thread.
Sprang makes a really stretchy bag.