I have written to Matt about sizes and this is his response.

Hi Randa,

Thanks for your message.

I have measurements and patterns for all the early Eribas (Puck, Pan, Familia, Troll, Triton) which had orange cotton-canvas pop-tops, so can make these easily.

However I sometimes need measurements and photos for the later Eribas which had light grey acrylic canvas tops.
I have patterns for some of these but not all, and some models used the same pattern as others. I am learning as I go!

Having recently replaced the top on a 1992 Eribacar, I have the pattern for this now too. (Admin note. I would advise checking with him first regarding the Eribacar in case the measurements he has are for a smaller/bigger roof size.)