Based on the Adafruit Resistor Helper papercraft resistor calculator designed by Adafruit with Mathew Borgatti.
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.