And now we even have a tutorial on how to use them!!
As with magnetic snaps, these fittings were designed for use on leather, so I've included a few steps to ensure longevity when you use them on fabric.
A BIG IMPORTANT NOTE BEFORE WE START:
These instructions begin at the point just before you attach the lining to the facing of the bag.
1. Place the flap of the bag in the closed position.
2. Find the horizontal centre of the flap and stick a pin through at the point where the twist-lock will sit. Push the pin through to the front of the bag body.
3. Mark (with a small dot) where the pin goes through the bag body. This is the vertical placement of the lock. (I use a Clover white marking pen on dark fabric. It disappears when you iron it, so it doesn't matter if you accidentally mark the wrong spot). 4. Use a tape-measure or ruler to check that the placement dot is centred horizontally as well, and then mark the fabric with a cross.
5. Using the twisty bit of the twist lock, mark where the prongs will go through the fabric, centred over the cross. (Apologies for appalling photos!!)
6. When you have to cut accurately through many layers of fabric and interfacing, it's easiest to use a knife of some sort, rather than scissors. I use my Olfa point cutter, but you can equally use a Stanley/utility knife or paper-craft scalpel.
Put a cutting board or block of soft wood (pine or even balsa) inside the bag body, underneath the placement mark.
Err on the side of too small (rather than too large) as you cut through all layers of the bag body on both of the 'prong' marks. You can always cut them larger later on, if needs be.
7. Use a scrap of thick interfacing (such as Fast2Fuse or Peltex) or several layers of fabric to make a support piece for the back of the clip - about a 2-3 inch square. Cut slits through the support piece as well. 8. Push the twisty bit (that's the technical term, isn't it...?) of the lock from the right side of fabric, through the slits in the bag body.
9. On the inside of the bag, push the support interfacing/fabric over the prongs (where they come through the fabric).
10. Place the metal plate over the back of the support interfacing and prongs, and then fold the prongs inward. If you can balance the twist lock on the table, a quick little tap with a hammer will help to flatten the prongs.
Ok. That's the twisty bit IN!
Onto the flap....
11. Using the top plate as a guide, centre the hole over the placement mark on the front of the flap and trace it through with a fabric marker. 12. Again, you will have more contol over accuracy - when cutting through several layers of fabric - if you cut directly DOWNWARD (rather than with scissors). I use a saddlers punch to cut two holes near each end of the oval shape.... (a slit with a sharp utility knife through the length of the oval would also work). 13. Use the sharpest small scissors you own to snip away the oval shape, including the pen marks. (If you have punched the two holes, you can easily snip from the edge of one hole to the other. By doing this on both sides, you have created a rough oval shape, which will only need a little bit of tidying up).
14.Ok. This is where my neurotic perfectionism comes in....We've just cut through centre-front on the bag. We're going to place a feature fitting, which is also the major stress-point on the bag. What we don't want is a feature point becoming the first place to show wear-and tear. Likewise, we don't want nasty little raw ends poking out through the centre of that lovely, shiny front plate.
I use a bit of Fray Stoppa around the cut edge of the hole to stabilise it. It makes the edge a bit stiff and easy to trim, and it stops further fraying. You may find another product that does the job (liquid embroidery stabiliser, perhaps?).
Let the Fray Stoppa dry before proceeding.
15. Place the front plate on the table and line it up under the hole you've cut. Give the (stablised) fabric another trim, so that it sits neatly around the lip on the hole of the front plate (with no overhanging raw edges).
16. A wee drop of fast/clear-drying craft glue on the front plate (spread thinly so that it doesn't goop out around the edges) will hold the plate firmly to the fabric.
Call me neurotic and ignore me if you will.... but I find this step makes it easier to put the back plate on (and it reduces the possibility of wear and tear between the fabric and metal).
17. Push the hole back over the lip of the front plate and press the fabric into the glue.
It should stay nicely in place.... (You can do any touch-up trimming that might be needed to eliminate raw-edge overhang for good!)
18. Pop the back plate on and fold over the little tabs.
Voila! Shiny, shiny and super-slick twist lock... that will never EVER pull through the fabric!!!
They're now in the shop - HERE!
I think this project would be a good Christmas present for anyone wanting to learn to sew, accompanied by a yard/metre of cute fabric (or a new sewing machine?). Just thinkin'....
(You may also remember that one year I wrapped my xmas presents in shopping bags instead of paper...? ) 
If all goes well in the final stages of lease negotiations on the new digs, I will be quickly scheduling some real-life pre-xmas workshops in swanky new premises. Please keep your eyes on this blog, Facebook, Twitter to be kept informed. (And if you're on the mailing list, keep checking your junk mail folder!!).
