Where do you get scrap wire for making pigtail connections e.g. when wiring a switch?
You generally want solid core wire to match what you're working with in your home. I keep rolls of #14 and #12 cable on hand and cut off those as needed. You may be able to purchase pre-cut pigtails, but they're probably quite expensive as compared to regular cable.
Also note that 250 ft. rolls are far more cost-effective than short rolls. It's far cheaper per foot and you might be surprised how quickly you go through it as a homeowner.