You should contact Moira Taylor at the University of Nottingham, who deals with the Phantom plans and building instructions. Her email address can be deduced from firstname.lastname@universityname.ac.uk
The original "plans" were really full-sized paper templates, which could be used for cutting out the plywood panels. Moira had those scanned several years ago, and I then converted those into 2D DXF files which I nested for 4' x 8' plywood sheets, so if you can find somebody with an NC cutter you can make up your own kit.
I obviously still have all the files, but the agreement is that permission and royalties go via Moira.
Charles