Hi I have to make a 2 door unit to make to store valuable equipment in so I am wondering what to use. Should I go with 18mm plywood or 18mm MDF. What should I do regarding doors they are 400mm wide by 1500mm high so should I double sheet or just brace around the edges and cross brace and also what should i use for the lock and hinges as these need to be able to keep somebody with a crowbar out. Grateful for any advice received.