just worked out which post offices are currently open and sent the first mould out to the states this lunchtime.
We're basically up and running

postage for a 66x33 is £7.
The mould was £20
Unless you want something drastically larger - then it seems a fair price and saves mucking about with calculations all the time.
They use about 4x more plastic then than the sliding moulds and take around 8 hours to print - 4 x longer.
Mind you if the cost of filament keeps going up I'll have to change that - but until I run out of what I've got at the moment - that's the price.