Nope, you can't purchase one, you gotta make it yourself.
Unless you are one of those who can remember the entire color code for 4- and 5-band marked resistors (test later on how many possible combinations there are; I'm still working on wiring up CAT-5 correctly), you need the help of a reference chart or you can use the handy papercraft Adafruit Resistor Helper. Need a cool thing to wear to work or school? What better time to make or give the gift of a tie? Of course, for the geek and technically inclined, a hacked tie would be even better.
You can make a resistor tie from scratch but you can also repurpose old ties too. Do something with those old power ties to make them current.
I am just going to use a tie I found at the dollar store (really $2, it had a cool sparkly techno vibe in the pattern) and make a few quick mods to implant the papercraft resistor helper.
CAUTION: Know how to use pointy and sharp things like scissors. Know how to sew, press and iron safely.
Step 1: Materials Needed
Raid the office supply cabinet for the following:
Thin cardstock or heavy paper to print out the color wheels
Iron-on transfers for light or dark material depending on the choice of tie
Ink-jet printer to print image on iron-on transfer blanks
Brass paper fasteners, the one that look like a tack but the front tangs split open
Clear packaging tape or laminator
Fusible iron-on interfacing or embroidery fabric stabilizer
Simple sewing skills and necessary sewing notions, punch awl and seam ripper optional
Step 2: Make the Resistor Helper
Download the PDF of the resistor helper from thingiverse or github.
Print out one copy for reference.
Print out one more to cut up and assemble the color wheels.
Print one copy out on your iron-on transfer paper. Know how to use your iron-on transfer paper. The one I used is for application on dark materials. It requires that the image not be reversed and it must be printed on the surface that will peel away from the backing sheet. It is applied directly on where you want it to stick.
Step 3: Wheel of Resistance
You can roughly cut out each pair of color wheels and glue the corresponding parts back to back. Place under a weight like a telephone book to keep them flat while the glue dries.
When dry, trim close to the edge design.
You can run the color wheels through a laminator or just apply clear packaging tape over them. This will increase the durability and strength of the color wheels.
Laminate both sides of the color wheel. Trim off excess tape.
From the iron-on transfer print, cut out the separate panels for the sides of the resistor helper. You should have two pieces, the 4-band and 5-band sides.
Step 4: Tie One On...
Time to start dissecting the tie. Use a seam ripper tool since that is almost as good as a scalpel in working with delicate tie material. Okay, we've got real polyester here instead of silk.
Break the bar tack that holds the back of the tie together near the bottom. Splay the tie out up to where the tie holder label is. You might need to free up a side of the label too.
Using one of the resistor holder side panels as a size guide, position it on the tie so that you can see you have access to that much of the tie.
You can place the resistor helper on either side of the tie. The preference is determined by which hand the wearer will prefer to use to access the thumbwheels.
Step 5: Open Necktie Surgery
Transfer the markings where the color wheel windows will be to the interfacing.
Cut out that piece of interfacing.
We need to restore structure to the tie by applying a piece of fusible interfacing to the tie's outer fabric where the original tie interfacing has been removed. This also reinforces the tie fabric so we can cut out the windows for the color and number values. Also, the paper fasteners will be inserted through there.
Cut a piece of fusible interfacing the size of the side panels. Fold in half and mark the fold so it is easier to see.
Line the interfacing up with the fold in the edge of the tie. I had to trim the front a bit so it would not intefere with the seam and fabric tie liner at the point.
Apply heat with a clothes iron set a moderate heat to bond the fusible interfacing.
Step 6: Press On...
Line up the side panel iron-on transfers on the tie to see where they will be applied.
On the back of the tie, the transfer bled over the back of the tie seam. I applied it in place and then cut it open after the iron-on transfer cooled. You still need access to the inside of the tie. It will line up nicely when sewn back together.
It is easier to apply the back panel first because you can line it up by seeing where the interfacing cutout is. Tack in place along the edge first. Place a piece of parchment paper as a cover liner to keep the iron-on transfer from sticking to the iron.
Fold the rest of the tie in place and complete applying the back panel iron-on transfer.
Open up the tie and lay it flat. Line up the opposite side panel. Apply iron-on transfer with the clothes iron and parchment paper cover layer.
Step 7: Get to the Point...
Ensure that there are no hanging chads so that the count will be accurate.
Use an awl or something sharp to poke holes for the paper fasteners. Using a drill or drill press would be overkill.
Step 8: Do the Split...
Work the fasteners in place through the tiny holes you poked with the awl.
Use the awl to poke holes for the fasteners in the color wheels. Have them arranged in the order you will be placing them in the resistor holder. Poking a hole in the center of the color wheel destroys the reference label so have them oriented facing the way they will be installed.
Refer back to your reference printout one more time to make sure where the color wheels go.
Mount the color wheels.
Push the fasteners to the other side of the tie. Split the ends and press flat to secure.
Step 9: It's a Wrap...
Here is the completed tie with Adafruit's Resistor Helper.
The front of the tie is the 4-band resistor reference. On the back is the 5-band resistor reference.
Now where did I put that pocket protector?
Step 10: Dress for Success...
Engineer or slacker knot.
Impress the gang at karaoke night with your resistor value divining skills.
Use as a conversation starter or indulge in games of resistor pong. This does not replace the need for the "EEs do it with more resistance" bumper sticker.
Need to decode the color stripes on a resistor? Usually you can say "There is an app for that" but now you can say "There is a tie for that!"
CAUTION: As with all ties, do not wear when working near machinery, open flames, or eating soup.