I am refurbishing an old aerobar that I got for a few dollars. The rubber pieces are old, hard, cracked.

I need new elbow / forearm pads. Where do I get black colored dense foam rubber of the right consistency and thickness?

Also need to replace the foam rubber covering (one piece, not a wrapped tape). Although I can go with wrapped tape if I have to.

For a cheap replacement elbow pad, try a blue foam camping pad sold at walmart for a few dollars. Use a sharp knife to cut out the pads.

Forget the single piece foam bar cover. Use bar tape.

Refrigerant (AC) line insulating hose. available at hardware stores.

Any good bike shop should have replacement pads. If not check there J&B catalog. I make my own from 1/4" thick mouse pad. You can purchase upholstery glue in a spray can like paint in the hobby section of any big box retailer. Just cut your material of choice larger than the plastic mount you will be attaching the material on. Clean and prep the plastic surface with alcohol. Spray the glue on both the material and the plastic and allow time for the glue to get tacky. Stick the material to the plastic and press them firmly together. Allow the glue to dry according to the directions on the spray can of glue. Take a razor knife and trim the material to the edges of the plastic.

Profile sells circular replacement pads for the century aerobars, or the flatter ones for the more expensive models which aren't so circular.

https://www.tri-zone.com/Products.html?cat=80