Having failed to find anything suitable for the foot of the mantis I decided to try making a mould and creating my own foot pads from polyurethane. This was the first mould and the first pour I tested. Unfortunately I got the quantity wrong, but it was a pretty successful test. I poured two types of hardness, shore 70 and shore 60, initial thoughts are that the shore 70 will work best.
The product I'm using for these feet is PT Flex 70. It's a fairly easy product to use, although the pour time is only 5 mins, so you need to work fast! De-mould time is approx 1 hour.