That would have been back in the day when
GW actually cared about the hobby.
IIRC the legal stuff on their website says that copying, even for personal use, is verboten.
Far Seer
My concern with Vaseline is that
afaik it is petroleum based.
It may have no adverse affects on the moulding material, but it may do.
I have seen vaseline advocated for use in sculpting with
GS but again I don't know what the long term affect would be on my clayshapers.
I have recently bought some KY jelly as I understand it is waterbased so that might be a useful alternative. I guess it will wash off the mould easily and not harm the reusable plastic.
Just to go
OT for a moment, but with regard to stopping
GS sticking to the work surface:
I decided to get a couple of silicon keyboard covers which are really cheap.
Borrowed one to put on my table top to see if it would be better for work with
GS and it works a treat,
Whereas I was having to wet the glass to prevent
GS sticking when rolling etc, nothing is required as
GS doesn't stick to the silicon sheet.
Hope that the tip may be of use