How heavy is the weight?
My weight (TD125 MkII) is a 45 adaptor attached to the flat side of a medium-small brass Mapleshade cone (3 tiny spots of poster tack) and the total weight is approx. 8 ounces.
The DIY weight is as symmetrically balanced as I could get it (pretty easy as the flat side of the cone is the same shape/size as the 45 adaptor) and it’s non-magnetic.
I’ve tried heavier commercial weights with various mats and the 8 ounce unit is all that is needed as I heard no improvement with heavier weights (sometimes the opposite - mine is a "sprung" design).
I did not experience speed problems though within the weight range I experimented with.
I was initially concerned about increased main bearing wear and strain on the motor with heavier weights.
DeKay