This abacus ring is based on a traditional Chinese abacus(suanpan), 2 top + 5 bottom bead configuration. Works for decimal and also hexidecimal numbers. There are stories of people that can do complex calculations on an abacus faster than another person using an electronic calculator.
Pinky ring not for you? Try the slide rule bangle bracelet instead.
DISCLAIMER: Not yet approved for use on SATs or any other standardized testing.
Step 1: Getting Crafty...
You will need metal crimp beads. I picked the smallest size they had at the craft store because I wanted the abacus to be small.
Although the beads look tiny, when they are on the frame, they can still be easily manipulated with just your fingers. Assembling the abacus was another story.
Head pins or thin stiff wire. These are probably stainless steel or some kind of alloy steel that solder sticks to. You could use brass or copper wire for a different look. Gold plated hardware might be available.
You will need the usual soldering tools and a fine tip soldering iron.
Since this is in contact with your hands, use lead-free solder. As with all jewelry in skin contact, know if you are allergic to anything.
Have a nice pair of wire cutters to trim the excess wire after soldering.
I used masking tape to hold down the parts as I soldered.
You might want to work under a magnifying unit to do the soldering on the close joints. Not as bad as SMT soldering but still a little tricky as all the parts want to move independently.
You might want to work in a nice, well lit, clean, clear of obstruction, well ventilated and flat working area. Wait, who are we kidding?
CAUTION: Parts are tiny. Many will end up on the floor somehow. Vacuum afterwards. Same goes for the tiny metal shards that you clip off when your trim your solder work. Solder fumes are bad for you. Soldering irons and freshly soldered parts are hot.
Step 2: Easy As 1,2,3...
Like all things, this was not really thought out and was done as we went along.
These head pins have a head on one end. You could just use a pair of pliers to make a 90 degree bend at one end.
This helps align your first post or column rod onto the top header rail.
Tape in position. You should really do this over a more heat resistant surface like metal or tile. I just happen to use cardboard as my sacrificial worksurface layer. There is a fire extinguisher under the table.
Solder your first pin in place.
This will take a little more heat and solder to get a proper joint on thicker metal wire. Tack solder in place first and then you can go and fill in the solder on the other side or flow it between the pins.
Continue to position and solder in a total of 10 posts. You should place a bead or two on the pin so you can get the spacing right for the beads to move freely.
I thought I could eyeball it and then bend the pins apart if needed to make room. The soldered joints makes that part pretty non-adjustable. I fussed with resoldering a couple of pins that were too close for the beads to fit.
Populate each pin with 2 beads for the top portion of the abacus.
Note that these tiny beads are very small and hard to grab with big fingers, let alone manipulate them in position to align the hole so you can thread them on the post.
By the way, there is a 99% chance of tipping the whole open package of beads and spilling them all over the place because you caught the package with the cord of your soldering iron or knocked into something else pushing into the package. Tape it down too,.
Step 3: 2nd Verse, Same As the First...
Use a full head pin but offset the excess and the head tip to one side. That will form one side of the ring that goes around your finger.
Solder the separation bar.
Try to keep the beads away from the joint and watch the solder flow so it doesn't stick the bead in position. If you have too much solder, you can remove it with a solder sucker or wick.
Thread on 5 more beads to each post.
Put a bend in the end of the post when you have filled that up with the 5 beads. It helps a little to keep the beads on when you move it all around to thread beads on the other posts. You can also use a bit a tape to temporarily lock in the beads.
When you have all the beads on the bottom portion, solder in the bottom bar with the head pin excess and head tip offset to the other side.
Trim the excess post leads. Watch for flying shrapnel.
Step 4: Mathematicians Do It With More Precision...
Use pliers or a hammer to form the abacus frame into something more rounded to fit your finger.
Bend the long leads around to fit the size of your finger.
You could also solder on some more wire to form a beefier ring.
Keep your pinky up or wear it on any other finger.
Look up any instructable on how to use an abacus.
Someone should make one with a wood frame for the ibles woodworking contest.
I guess I could have been real geeky and made a magnetic core memory matrix in the same way. Too much work.