ive finally sussed it
ok what do you think! (the how 2 is at the bottom)

ok what you need
1. a canvas at the appropriate size for the model, i got mine for the works for £5, (40 x 50)
2. grey rattle can - halfords grey primer
3. a blunt soft pencil
4. a long ruler
5. yellow paint - games workshop for me
6. some grey tone pastels - again from the works
how too....
step 1 - very simple, spray the canvas grey
2 - when dry draw squares on the canvas in pencil, 15cm square is approx correct for 1/32
3. using cheapo masking tape, mask lines approx 1cm wide, for the curve i used the esge of a plate, then paint it yellow - the games workshop stuff is thick so only uses one coat
4. when dry, use ramdom grey - black pastles to add a bit of dirt and hey presto