So I am wanting to build a diorama using some plastuct materials.

I am wanting create a partially destroyed factory in 28mm scale(close to "O"scale.

My question is related to the different sizes that you can buy the parts in. For example for the ABS I-Beam there are several sizes numberd from -2 to -24. I believe the -12 (3/8") is the correct size for "O" scale but am not sure.

Can anyone help me out?

Also if you decide to use -12 for one part should you stay with -12 for the rest of the parts?

Thanks,
GG

Hi, i am not going to do the conversions from inch to railroad scales now, but isn't your whole question answered by using a scale converter?
http://ebasic.easily.co.uk/05800C/03D03B/scalecalc.htm

Also i think that you certainly can use different sizes. Of course always in scale and reasonably

Claude