German rolled steel armor appears to have been very smooth up to about 80mm thicknesses. Heavier plates do exhibit occasional pits and scabs on the surface, and I will sometimes depict these by chucking a Dremel burr into a pin vise and gently adding random pockmarks to the surface. I have more control with the pin vise, and it's always easier to stop short than it is to putty over and sand away too much texturing. There was a fad in the late '80's/early 90's to pockmark every armor surface with a Dremel power tool, and like all fads, it was frequently overdone (like preshading and paint chipping today). The power tool often ran away in the user's hand, leaving an awful skate mark on the surface. For a flashback to those days, look at any Verlinden resin Sherman conversion hull.
For cast steel texture, there are several viable techniques, applicable to different foundry finishes. Applying liquid cement and stippling the soft plastic with the bristle tips of a nylon brush will create a very pockmarked texture (suitable for that seen on some Russian wartime castings). Gently sand the textured areas, and you will get irregular flat areas and small irregular pockmarks, which looks pretty good for some US turret or hull castings. If you want an evenly pebbled finish, a product called Cast a Coat is an adhesive brushed on the surface, then sprinkled with a fine granular material. You can also use Mr. Surfacer, a thickened paint that will hold a similar texture if you stipple it with a nylon brush (you can make a home-brew equivelent by adding ordinary talcum powder to any enamel paint). This additive texture also works well if you want to texture resin, wood or real metal.
Prewar French castings were extremely clean, and might not need texture at all, or perhaps just a slight orange peel texture (peacetime factories could pay attention to things like exterior appearance).
Sometimes textures could be very apparent. The Maus gun mantlet has some very grainy curved surfaces, with the side and top edges polished out with a hand grinder to a near polished finish.

The Irregularities would be found in the CAST steel.... Anything made in a Sand mold will have a mildly rough surface

I once worked in a shop that specialized in building and erecting cement mixing factories. We worked with angle iron, C-channel and rolled or sheet steel. Most of the steel that I worked with was either 20 or 40 ft long by 8 ft sheets. The process of making rolled steel hasn't changed much other than the ability to remove or control the amounts of impurities in the steel.

The steel stock that I worked with was fairly smooth and even. Even at the high rate of production that happened during WWII the factories in the US were not being bombed daily and probably had a high quality rate (for the day). The edges that were torch cut by hand are going to be ragged, the welded areas will have splatters of steel up to 6 inches on each side. These little beads would be scraped off with a scraper or other type of power tool.

I didn't see much pitting but it probably happened back then but still not by much. Most 'pits' in the steel were where tools, lifting devices or something knocked into it.

In 1/35 any type of texture would be overkill in my opinion. I tried the glue technique one time and was not overly impressed by it. I don't think that I will do it again in the future.

If I may, I'd like to throw a spanner wrench into the gears. To my eyes, rolled armor plate found on WW2 era tanks is very smooth -- with very little pitting or irregularities. To add the amount of texture that the liquid cement and sanding thereafter, would impart I believe would be exaggerated beyond what should be visiable in 1/35.

This is my observation. Have a look at these two Panthers and this M4A3

http://tanxheaven.com/dmk/Panther/pantherdmk.htm

http://www.toadmanstankpictures.com/m4a375.htm

Often if you look at surviving tanks, the surface irregularity is caused by layers upon layers of paint. Look at how smooth the skin of the M4A3 really is!

The method described is what I do to add texture to CAST metal parts. I think it would be overkill for rolled armor plate, in my honest opinion.

Take it for what it's worth but look at the photos yourselves.

Rgrds, Roy

Thanks!
But Zokissima is right!
Why don't you show us your technique with some photos?

Do you have any pics of what this finished product may look like? It sounds appealig, especially to those like me who do not have a motor tool to scuff up a surface.

Hello modelling friends.
This post is in regard to recreating rolled armor plate on plastic scale models. One technique I use is to spreat a little tamiya liquid cement on the given area. Once its dry, use a little steel wool or scotch brite pad to lightly sand off the dried liquid glue revealing a nice uneven texture.
If you guys have any other tips or techniques please share them here.
Thanks

~Martin