I made the best mat myself. It is not "UNIVERSAL" mat, as there is not such thing since every record sounds different and mastered differently.
I made a mat to tame some of the Hard Rock records that have distorted highs.
I took cork shelf liner with self-adhesive back and attached it to the old and heavy LP record.
No I did not make donut out of it, you may try if you wish.
I just thought along the lines of: Since heavier records sound better than why not make all my records at least twice "heavy" by laying them over another thick record.
That alone would be to "ringy", so I added a layer of self-adhesive cork liner to the bottom of that defunct record.
I use this mat to reduce harshness of some records and in extreme cases I flip it cork side up to get even more muted response.
This is an easy project and might provide benefits for some of your harsh LPs (Slade-"Slayed" for example).
In conclusion: I realized that to have one "universal" mat for TT is not a real solution simply because there are to LPs that sound alike.
