In 2004 the 14 month old motor mounts on my 2003 Mazda Millenia broke. The 3 mounts would cost well over $200 each.
So I got some broken (junk) ones from a salvage yard for almost nothing.

I cut & scraped all of the rubber off. Then using cardboard & duct tape I sealed them up with only a small part exposed, so I could pour the rubberish material into them.

From Eager Plastics in Chicago, I bought a 3 pint PMC 790 kit. This is a rubberish urethane product. The hardness is measured in "shores".
90 SHORE is what I used. If I did it again I'd use 70 SHORE. It is a 2-part mixture product.
When I had all 3 motor mounts ready, I mixed and poured the urethane into them and allowed them to set for 24 hours.

That was 12 years ago. I still have the car (as a spare, even though I don't drive it much anymore).
The Factory mounts ONLY lasted just over a year.
The ones I made (or repaired) are still going strong.