I do zimmerit the hard way, but it works. I use squadron white putty and I use Tamiya's Photo Etched zimmerit tools. For my method, you need Tamiya extra thin liquid cement, paper towls, squad putty white, a razor blade, masking tape (tamiya 3mm tape works great too!), and the zim tools. FSM's 2002 May edition has the works if you want to look up zimmerit how to.
SOME THINGS YOU SHOULD KNOW BEFORE DOING THIS!
You need some serious ventalation when doing this. The putty and cement smell really bad, so your best off doing this outside. Another thing is you will want to cut or sand off all bolts and obscerities before applying the putty. You'll see why when you read this. Sand down the places to be zimmed so the putty has something to "stick" to. This is especially true when using epoxy putty, I'm told. Enjoy.
1)I mask off the section to be zimmed and I make it about the size of a large postage stamp-1/2 inch X 1/2 inch or so.
2)I blob a dot of squad putty about the size of an M&M candy in the center and smooth it out over the surface with the razor blade. Why the razor blade? Because it's metal and the putty doesn't stick too bad to the blade. After smoothing, wipe any extra putty off the blade by putting the paper towl on the edge of your table and swiping the putty off.
3)The thin layer of putty should be about 1mm thick. It's going to start drying fast on you, so this is were the extra thin liquid cement comes in. Coat the thin layer of putty with one brush-full of cement and the putty will become playable and it will absorb the cement. CAUTION! You need some serious ventilation for this and you might want to do this outside.
4)Now that the cement has acted as a retardant, you just bought yourself more zimming time with it. The Tamiya PE kit comes with to different size zim tools. One with .5mm grooves and one with .7mm grooves. I use the .7mm tools. It just looks more realistic for 1/35 scale armor.
5)Now slide the tool into the putty horizontally about 2-3mm across. Stop but don't take the tool from the model. Now move the tool up a little, about .5mm up and start over. Doing this makes the distinct colums of zimmerit.
6)once the process is done, swipe off the putty off the tool, just like the blade, and apply a little liquid cement to the tool to soften the putty and wipe it off.
7)Repeat and it will be done before you know it. I don't use epoxy or poliester putty because I've never tried them and I don't want to experiment with a model, but I will eventually switch over once I find it...
I'll try to get some pics up...