I made a copy of the Seal Mate out of a soda bottle. I was so amazed how well it worked on every leaking fork seal I came across that I spent the money to buy a Seal Doctor that makes the job 10x easier, faster, and less oil leakage. The trick is to bounce your forks several times after cleaning to reseal.
I am certainly a believer. It's quite crazy to think the money spent on replacing seals that just needed a good clean out. I've saved 3 forks from leaks with a homemade one.