I had opened this question in the main Sketchup forum, but following a suggestion I have copied it to 3D printing, as it relates to adjusting the size of a sketchup model so it will print to the correct scale size;

I am designing models, currently mainly road vehicles for

3d printing, for T scale models railways (1/450 scale). These models are

small - in this scale a short wheelbase Land Rover scales out to just

8mm in length. (some that I did managed to design and print - http://www.shapeways.com/shops/t450 )

Herein lies my problem - I am not sure what size to use to initially create my designs.

At first I tried using the actual size of the final model, but that failed because the circle tool does not work at those sizes.

Then I tried at either 1000x (this being convenient as I could just

convert mm values to m), or at full size of the actual vehicle. When

doing this I set the measurement and angle accuracy to the maximum

first. The problem with this was when I then used the scale tool to

reduce the size of the model to 0.001 or 0.00222 for the actual 3d print

size the models do not always scale smoothly and can often end up with

holes where some of the faces just dissappear completely. I have tried

scaling the model as is, and also converting to a component first, but

either way can get the problem.

I would be grateful for any advice from anyone who has experienced

this problem, so that I can create my small scale models with curves on

the bodywork as required.