I recall seeing one of those fuselages being sold at a club auction once. It was polyester glass fibre, made with chopped starnd mat and weighed a ton. The engines used were Merco 61s and the numbers produced must have gone a long way to keeping Merco in business.
https://www.arrse.co.uk/community/threa ... ts.149729/
Back in the late 1980s I was shown a video of a demonstration to senior officers in which a MATS-A filled with explosive hit a Saracen armoured car. The explosion did seem rather large, and it transpired that additional explosives had been placed in the Saracen to ensure the demonstration was suitably impressive.
THe MATS-B appears to still be in production:
Mike_K, that 'mouse nest', the wadding, which is probably a quick and easy way of providing an anti-vibration mounting for the fuel tank, looks like a piece of rubberised horse hair. It was often used by the Ministry of Defence for protection of delicate equipment in the 1960s and 70s, and is still available for reupholstering old furniture and making model railway scenery.