Diorama Craters were available through a mail-away offer where you had to collect a set number of points (similar to the Z-Point scheme). Unfortunately, they were made from very brittle plastic and few have survived to this day.
Contest Prize Zoids
Thanks to Zmaster76 for the following information. They write:
I believe these were contest prizes issued to the end of the line after the Super 1,000 Zoids had been put on sale. They came in plain white boxes with instructions identical to their regular versions. There seem to be at least 7 in the set (although I haven't seen the Zoidzilla before so if I missed that one I could well have missed more): the three you have pictured here as well as a Krark, Zabre, Znake and Redhorn. Since the line was dead by then, I doubt there are more than a hundred or so of each in existance.
Richard has kindly supplied some further information:
The translucent Zoids you have pictured in your guide were part of a Zoid-designing contest. Different areas had different Zoids as prizes so I'll give you a list of what have managed to find out.
Area 1 (Zoids coloured gold and black) 1st Prize = Zabre, Shield Tiger and Krark 2nd Prize = Unknown 3rd Prize = Unknown
Area 2 (Zoids in regular colours) 1st Prize = Complete set of Super 1000 Zoids 2nd Prize = Set of Super 1000 Zoids excluding Shield Tiger and Spinefin 3rd Prize = Unknown
Area 3 (Zoids coloured translucent and black/silver) 1st Prize = Zoidzilla, Krark, Zark, Znake and Tarantulon 2nd Prize = Zark, Znake and Tarantulon 3rd Prize = Choice of Zark, Znake or Tarantulon
Area 4 (Zoids coloured translucent and black/silver) 1st Prize = Unknown (2nd prize may infact be the 1st prize, if so i'm unsure of the 3rd prize) 2nd Prize = Zabre, Redhorn and Shield Tiger 3rd Prize = Choice of Zabre, Redhorn or Shield Tiger