Her fascination with delicate construction, combined with the skills she was developing in art and craft subjects at school, led her to train as a dental technician at Manchester Polytechnic, now Manchester Metropolitan University. Back in the 1980s she remembers there were 400 applicants for 16 places.
Disillusionment came with a job in a dental laboratory. She was working with unqualified people on repetitive, production-line tasks with no chance to use the skills she had, let alone develop new ones. After a year she went off to America as an au pair.
But the desire to use her training persisted, and in 1991 she joined the Army as one of its few female dental technicians. She developed her skills and learnt to make complete appliances. "It was the first time I ever felt valued," she says.
Karen estimates that she would take a pay cut of up to pound;10,000 outside the service. And the Army is sponsoring her through the Diploma in Professional Studies, a course which involves 4,000 hours of study and 11 days at university.
She aims to become the Army's first female laboratory manager. Later on she wants to work in a hospital as a maxillo-facial technologist, helping surgeons to rebuild a patient's face after accident or disease.
She would not work in a private lab again. "Lab managers are undercutting each other. You may as well work in a chocolate factory," she says.