These sites will give you some ideas:
http://www.bta4wd.com/category12_1.htm
http://www.tanami4wd.com.au/
Or these comments from someone that made one may help:
"I made and installed a set of drawers for my Landrover Discovery last year.
2 drawers side by side with a lift out lid on each side that sits flat where the rear side pockets used to be.
I used xtra heavy duty full extension slides and aluminium sliding door locks to keep the draws shut. Tons of storage, both in the drawers and the flush side pockets. A large flat area on top of the draws for loading up eskys & gear etc and still get to stuff in the drawers, best thing I ever did.
Constructed from 12mm ply, glued & screwed and then contact glued on a very thin type of carpet that is used for lining.
I made a cardboard template of the shape of the rear luggage area and used that to make sure I got a perfect fit. It is bolted into nuts that were existing in the vehicle. Can be removed easily ( I only have it in when camping), takes about 20 minutes to re-fit."
