I've had good luck with  Apple Lisa's, Processor Technology Sol-20s,
Dynalogic Hyperions and a TRS-80 model II keyboard.  I make my own with
weather stripping (sticky on one side), two sided tape and silver gift
wrapping (mylar).  I would re-use the original plastic disk (after cleaning
them up) or I cut out overhead projector transparancies if I had to.  It is
a chore but I made hundreds once and am almost out now.
Here's a pic:
  I haven't had the greatest success with the Mylar
blankets on my Tandy
 6000 keyboards.  Some of the keys would act flaky and result in garbage
 characters on the screen.  I had to replace those problematic keys with
 original discs.  But, I rebuilt a Model II keyboard where the blanket discs
 work fine.  I think the properties of those keytronic discs are slightly
 different.
 Pete
  On Dec 12, 2016, at 9:55 AM, Kyle Owen
<kylevowen at gmail.com> wrote:
 If it's not too much trouble, emergency blankets (aluminized mylar, I
 believe) work well for these keyboards, so long as you get them in the
 right direction, mylar side towards the keyboard. Seems like you could 
 buy
  those, then stick them on the mylar and quickly
cut them out.
 Kyle