Playing with jewellery ideas, I decided I wanted to be able to secrete away something special. Heavily inspired by masynmachien's layered acrylic rings in form, I came up with a modern take on the Victorian obsession with locks of hair, and a ring for carrying a hidden micro-SD memory card.
I used poplar plywood and mahogany veneer for these rings, but there's no reason why you couldn't use acrylic for your versions, or even mix-and-match layers of both acrylic and wood.
So, on to the Hidden Memory Rings...
I draw my designs in InkScape, and they are scaled to fit Kitewife's slender fingers.
To save downloads, I've put both rings into the same files - SVG, PDF and the ECP files that my cutter uses.
A note on the colours:
To keep cuts in focus and aligned properly, I do the vector engraving first, then cut out the waste pieces, then the main pieces.
The way I set up my cutter, that means do red-lined engraving first, then cut out the blue-lined waste, then the black-lined main parts. That way, it's the waste that risks dropping through the cutting bed and getting damaged by extra cuts as the laser continues its job.
In case you haven't got the facilities to do a laser wood-cut, I've created a file that you can use to get your files cut online (attached to this step, works out about $16 for the two rings). The file for online contains parts for both rings, in 1.5mm plywood instead of the mix of plywood & veneer. That means you'll need to glue them slightly differently - see step six.
I used 3mm thick poplar plywood for both rings, with a piece of 1mm thick mahogany veneer in the Memory Card Ring.
The glue is ordinary PVA wood glue.
I did my cutting with a laser cutter, but if you don't have access to a laser cutter, you can use the PDF files to cut rings with a fine coping saw.
The rings need firmly clamped, between scraps of wood.
You'll need a range of sandpapers, and your personal choice of finishing - wax, varnish or (if you are using acrylic) you may want to flame-polish the rings (see masynmachien's instructable, or this fine example by Steveastrouk). I used a nice oil finish.
Don't forget to delete the parts of the cutting files that you don't need (for instance, if you're cutting the Locket ring, delete the memory ring pieces).
Also, if you are cutting the Memory Card ring, you'll have to cut the central layer of veneer separately, otherwise you'll end up wasting materials.
(Interesting observation: the 1mm mahogany veneer took as much power to cut as the 3mm poplar ply, and the flare at the cutting point was much brighter than it is for the ply.)
I hadn't used mahogany before and I learned:
Mahogany is hard - it took the same power settings to cut 1mm mahogany as it took to cut 3mm softwood ply.
Mahogany has a thick char layer - the sizing to fit the memory card was very neat, and while it worked first go in a card prototype, the char layer in the "real" version was thick enough that it made the gap too small (see the first photo).
Veneer is not plywood - even though the wood is very strong in blocks, it is brittle when the grain crosses thin sections. Gently sanding off the char layer caused the demise of more than one piece of veneer.
Thin layers are sensitive to moisture (more on that in the gluing step).
Line up the layers, apply liberal amounts of glue, and clamp the layers.
If your clamp has metal faces, use scraps of wood to stop your rings being marked. As you clamp it, the glue will ooze, but you can wipe the excess off easily with a scrap of tissue or a damp cloth.
If you are making the Locket ring, you should only glue the central layer to one of the outer layers, and let that dry, before you put the secret thing in the space. Once the first gluing is dry, and the space filled, you will need to be more careful with the second gluing, so that it doesn't spoil whatever you are hiding.
If you are making the Memory ring, slide a scrap of the veneer into the gap at the bottom of the ring, or the pressure of the clamps will close it up.
The veneer, being thin and single ply, is sensitive to temperature and moisture - as soon as you add glue, the U-shaped piece of veneer will start to open or close slightly, depending on exactly which parts swell first. The parts I cut tended to close, which is a problem because the gap becomes too small for the memory card. You need to clamp the parts quickly and firmly to stop the veneer sliding in directions that could cause problems.
If you're going to get your parts cut online, you'll find yourself with more layers than you might have expected from the pictures so far.
For the Memory Ring;
You will have seven layers to glue together.
Six of the layers are the same shape, one has the cut-out to take the memory card. Glue the six layers into two blocks of three, then sandwich the cut-out piece between them.
For the Locket Ring;
There are ten layers in the file - eight with the holes cut to make your secret space, two to close off that space. You don't have to use all eight layers - you can use fewer layers to suit the size of your finger and the object you're enclosing.
A light sanding, finishing with the finest grade you have, will smooth off your ring and reveal the colour of the plywood and veneer from beneath the charred cuts. Don't be too brutal on the faces of the ring, though, or you'll lose the design.
After that, the choice of finish is personal - wax, oil or varnish will all bring out the colours of the wood.
I decided to use two coats of Danish Oil, wiped on and off with a soft cloth, and left to dry overnight in between - it improves the feel of the wood, protects it from water damage, and really made the dark mahogany stripe of the Memory Card Ring really pop out.
I case you haven't worked it out, the microSD card slides up through the gap in the bottom of the ring, and then slips into the space cut in the veneer.
As designed, the card fits snugly, but even if is a little loose, your finger stops the card dropping out.
If you make your own Locket Ring or Memory Card Ring, please post pictures of them in the comments.