I can't say I've ever made one totally distortion-free, but what I do is first press my base in a smaller size lentil press, build my florals on top of that and then gently press after each layer in the final lentil press.
My theory is that if I keep pressing along the way, I don't have one final press where a whole bunch of molten glass is going to be squished at the same time, so less distortion. It works pretty well, but takes a few tries.
On the other hand, sometime the distorted petals are nice, more like pressed flowers....
edz
Lentil press and distortion?
