Apologies to all! I was wrong! Confused myself with the replica built by Clive Du Cros in the UK.K5054 was metal.
In relation to SAAA over the years, the requirements were laid down by the regulator. The alternative was to pay the regulator's charges to do the same thing with less experience in the world of amateur building. The requirement for the acceptable approved person in the early '90s was a CAA requirement to grant the authorisations required at the time. The cost of that person had to be covered from somewhere. The CAA was not going to cover the cost.
The organisations do not to force people to join". One does not have to be a member of SAAA to build an aircraft: the RA-Aus membership is their condition to grant a certificate to fly the aircraft in accordance with the CAO 95 series exemptions and they came about as a result of a parliamentary inquiry into the fatal accident rates in early ultra-light aircraft.