If you are interested in how i do zimmerit, here is the way that i have figured that works best for me:
I use Milliput, a hobby knife handle as a roller, a modified flat head screwdriver with the tip filed down at an angle to apply the pattern.

Step 1: scar the surface where you want the zimm, gives the milliput something to stick to
Step 2: roll the milliput flat
Step 3: Cut out the size you need
Step 4: place on model and roll it on using a roller
Step 5: Use a screwdriver to apply the pattern
Step 7: Continue until the surface you want zimmed it complete

I find this method ideal, the milliput has a long drying time to allow mistakes to be corrected, is easily sanded when fully dried, and is rock solid when completely dry and very durable. It is maybe a bit on the time consuming side, but the effects achieved i think are more than worth it.