http://www.vso.org.uk/volunteer/volunteer-placements/engineering-technical/vocational-trainers.asp
“Vocational trainer roles
If you are an experienced welder, electrical or mechanic engineer with experience of training and teaching, you can help to improve the quality of vocational training in developing countries.
You could be teaching mechanics in an all girls’ college in Nigeria, providing the students with a practical skill that will enable them to find work. Or, providing on the job advice to your colleagues, you’ll maintain and improve the standard of electrical and electronic equipment in a hospital in Malawi.
Experience required
Using your two years’ experience of metalwork, you’ll provide vital training in welding, metalwork and blacksmithing to students in Zambia. Roles are generally longer term, ranging from one to two years, and we also have occasional short term assignments for up to six months. For short term roles, you will need at least five years’ experience in your field and be available to depart within one year.”