For background, I'm 4 feet 11 inches tall. That means that from my hips to my knees is shorter than the length of a the driver's seat in a car. That means that without pillows to fill in the space, I either have to drive with my heel off the floor, with doesn't provide good control; or I have to sit without my back touching the seat back and holding myself up by the steering wheel, which doesn't provide good steering control and puts me too close to the airbag for safety. In SUVs and 12-passenger vans, I have to wear shoes with 2-inch heels or my feet don't touch the floor, even with the pillows. I can't hop into someone else's car and safely drive it; I have to bring or make-shift the proper accommodations.
One of these accommodations is a wedge pillow that makes the seat to seat back juncture tilt towards the steering wheel instead of away from it. I know newer cars have an electronic adjustment that does this, but my car is a '94. I even still have a functioning cassette player.
My old wedge pillow went with me for four years all over the United States. All those miles compressed the foam so that the wedge was barely serving its function. My back was starting to hurt. Not wanting to pay $12 for a new wedge that I'm uncertain will work and not having a spare $12 to begin with, I tried to make my own out some foam lying around.
I measured the dimensions of the old wedge. I took out my trusty Buck knife. I carefully, if crudely, hacked the new foam more or less into the proper dimensions, being carefully not to catch Sunday's nose or tail in the process. Sunday is the neighbor's friendly kitten, now, sadly, deceased.
I put the old cover on the new wedge and planned to sew a new one soon. This was in October. I haven't gotten to it yet. The new wedge works satisfactorily. Now if I can convince myself to work on that cover.