Before I put the three beads of Shoe Goo on my shifter, one of my prior experiments was to cut a piece of inner tube about 30 to 35 mm long (approximately), so I had a tube that I could stretch over the shifter. If you use the right tube size, it could fit tightly and not slip on your Aluminum shifter, giving you something that is cooler to the touch. But not sure if it would be easily grippable, it would of course cover up any knurling you do on the Aluminum.
This could be used to make a wavy one a larger diameter?
I got the idea for the three beads from Rohloff's original triangular shaped shifter, so I am not going to accuse them of stealing my idea to make the wavy version.
For long rides, I wear gloves. But for example yesterday I rode my Nomad to a couple of stores to buy stuff, about 7 km total and I don't bother to wear gloves for short rides.