Use PVA, available from any DIY store (Band Q), no screws just G-clamp and leave to set.
here is the drawing,
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http://muchos.co.uk/members/Angeloevs/edge.jpg[/img]
The inner 3mm strip/infill (not 2mm as previousley stated) can be any suitable material, even hardboard or 3mm MDF, tap T-edging into place using a mallet, (must have some radius on corners!). The standard thickness of panels used in most current leisure conversions is 12mm or 15mm and the T edging should be available in these widths but check first for availability. The edging should slightly protrude if possible but not essential. Dont forget to infill any area that will have items that will compress the panel such as door catches,etc. Get a courier to deliver if you have probs getting 3mm lightweight veneer, worth doing!
Alternatively, these doors were missing when I purchased my van. They are hollow, made from 4mm MDF and 3mm ply for the infil (cheap!), they are not veneered............they are emulsion. Three coats, flatted down between coats 1and 2. Hard wearing, any colour I like, easy to wipe and touch up if they get a slight chip. In fact......don't like the colour any more so doing them in a nice pastel blue. I personally do not like too many patterns in a small space and love the understated Westy interiors.
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http://muchos.co.uk/members/Angeloevs/doors190.jpg[/img][/url]