Buy some thick foam at a yardage shop. Buy some fabric at the same place. One yard should do. Cut the foam (I use huge scissors), and mess around trying it out over and over until it feels right. Then wrap the fabric, and hot glue it to the foam. I'm a horrible gift wrapper as you can see from the photos. (I used to pay my daughter to wrap Xmas presents for me). In hindsight, I might have lowered the area where my elbow rests. You could go crazy and build a real high one so your hand is in steering positon... Hmmmmm. Scroll down for all 6 photos.
Possibly, probably happened back in the 70's when I was pole vaulting. I still play tennis and racquetball every week, so it's no big deal for me...
Pretty neat! Don't be surprised if some fellow PC members ask you for one! For me, I need that extra seat room - could even use extra! But what I need is a pad to rest my elbow on the door while steering. After awhile, my boney elbow gets sore.