Can I ask how you would do uprights on the end of a van which get thinner from the bottom upwards? - Like these; http://www.rmweb.co....iding-door-van/
When looking at pictures of the LBSCR Van I'm doing, I noticed that they do this - not convinced just leaving them as a straight, flat piece of plasticard would look right.
Stick to LNER models..............
But seriously if you haven't got any 2.5mm x 2.5mm approx square rod, I'd laminate until I got the correct with (I'm assuming 2.5mm approx) stick the lengths into position. Wait a day until thoroughly dry then thin down one end until satisfactory.
Have never come across this in the models I've built.
Sometimes I wish these things came with instructions. You gotta make it up as you go along. A lot of the time you can only do so much, it's down to you how far you want to go.
You are the master of your own destiny. Post your progress here as it's a technique I may later need acquire.
The above is about as much use to you as a Easter chocolate tea-pot lol