Original engine mount. Rubber is torn-down.
Replacement parts are bad quality, rally/race parts are too stiff for road use, let's find a solution.
WARNING: do not use on critical suspension parts.

Removing the damaged rubber.

What is made of rubber and is known to be strong and durable? - A tire!
3 layers have been used here.

Using some rubber tube to protect it.

Some aftermarket parts are not up to the job.
JP Group/Quinton Hazell, lasted 2 years and 20'000km.

Howto:
• Remove as much as possible from the old rubber bushing (hacksaw, cutting knife)
• Cut multiple identical rubber parts to shape so the thickness or the stack matches the original part. Use the thread and avoid the shoulder or sidewall (angle grinder + mask)
• Screw the parts to a wooden plank and start trimming/drilling (use wood drillbits to drill through rubber, steel HSS/Co or even concrete carbide to drill through steel belts, and dremel grinding stone to trim holes)
• Press the parts together (vise or C-clamps)
• Drill a few holes to make the part less rigid
• Add a rubber sleeve (bike tube) hoping it will protect the belts from rusting and the TÜV guy from seeing it
• Replace part
• Test-drive