Wireframe cages are handy.    They’re pretty easy to make.   In fact, you can make a wireframe of any mesh’s level 1 polygons quite easily.    You start with your basic mesh, and apply UVTile UVs from the UV pallet.  

Subdivide the model 3 or 4 times so you have some nice detailed geometry to work with and store a Morph Target use “StoreMT” on the Morph Target pallet–we’ll need this later.  

Next, we want to mask the wire look.  This is easy–alpha 28.  It just looks like a square smaller than the the full alpha space.  

Use “Mask by Alpha” on the Masking subpallet and invert.   I filled out the mask top and bottom squares from my alpha because I’m going to want a place to drop in a logo later.  

A quick application of inflate and we have the shape protruding up from the basic object.  

If only Zbrush had a way to just save this frame and chuck the rest.  It does!   Remember that morph target we saved?   Well, there is another handy button on the Morph Target panel marked “Create Diff”.   Press it once and it will create a new tool in the tool pallet which is the difference between the existing mesh and its stored morph target.   Since we only raised up the wire shape, that’s the only difference and that’s what we’ll have left, leaving us with nice wireframe shape.

This isn’t really a Zbrush tip, per se, but I’m often surprised by frustrated modelers when they hit a wall saying, “This is way too complex!”   What they sometimes have failed to notice, in the pursuit of efficient modeling is that complex machines are often built out of assemblies which are made of subassemblies which are made up of even smaller sub-assemblies and ultimately out of individual (often cast) parts.   Observation of existing machines (and even disassembling a few) can improve your mechanical modeling.   To approach this piece of a leg, I didn’t start with the whole piece.  Instead, I recognized the sides were (at least in my concept sketch) just a mirrored pair of simple subassemblies.   A couple of cylinders and box (suitable beveled by masking and inflating.

Thanks to subtools, I only had to make one cylinder and one box which makes the basic strutSince I don’t plan to take this apart, I went ahead and merged these into a single tool–if I thought I would need to edit the diameters of the cylinders or something, I might have left these in pieces to adjust them.   (I do bend them, but fortunately I don’t need them in pieces for that.   To build up more of my machine part, I then take two of the assemblies plus a hollow cylinder to build up my next subassembly.

I haven’t built out some super machine with this yet (it will probably be the shin of some mechanical dinosaur when I’m done with it) but you get the idea–work with bite-sized parts and pretty quickly you can get some complex machinery (even without sophisticated texturing.)   This whole mechanical part was really created with just 3 simple forms, suitably scaled, deformed, and positioned.

Add a few more assemblies:

This trick really isn’t mine as much as a simplification of Lemonnado’s excellent tutorial on making Greebles with masks (Zeebles).   (You can view the full tutorial here.)   The point I want to show you here is that UV’s can play a very helpful role in making repeating detail.  Here we take a simple form, made up of a few polygons, and decorate it with a repeating geometry with very little work.

Step 1) Go to the UV menu (or the Texture Menu in earlier versions of ZB3) and select the UVTile button.   This will stack/overlap each polygon on top of the UV space.  Normally, overlapping UV’s is a BadThing™, but in this case, this is exactly what we want.

Step 2) Subdivide the object to get lots of detail–about 1M polygons (8 levels)

Step 3) Go to the texture menu and select a texture that would look nice.   A seamless texture will also look cool.  I picked built-in Texture 13, which looks tailored made for Greebles.   In one step, the whole object is covered with texture, 1 copy for each polygon at level 1

Step 4) Covert the texture to a mask by going to the Masking pallet and select “Mask by Intensity”.   For clarity, you can turn the texture off if you want.

Step 5) Inflate once or twice to bring out the geometry.

A little texturing and it has a nice tech technical surface.   Try this with other alphas or make your own after looking at Lemonnado’s Tutorial.

For years, model makers, whether working in the real or 3D world have known one secret to making things look realistic is often to add small details that represent the mechanical surface of the machine in question.   To speed things up, especially in the days when we worked in styrene instead of bits, small pre-made casts of mechanical “bits”, referred to as nurnies or greebles were glued to objects to make that object look “real.”   It’s a convincing illusion, even with the simplest model.   In this example, I’ve taken the simplest model I could think of, a straight edged cube.    For a real project, I would mix in six or seven nurnie types to increase the complexity of the surface, but for this example, I just used one, a hatch and varied its size.   Zbrush has a fast way to do this–it’s called the Mesh Insert brush.  

The Mesh Insert brush allows you to pick another model and just stick it to the surface of the model.   The “Brush Mod” slider controls how deep the object will be placed on the surface.   (I often slide it up around +40 to +60 so that the nurnie generally riding right on the surface.

The main point of nurnies is to save time, so you may want model for yourself a few Lego-like pieces to stick onto your next project.   I have a library of few hundred in various resolutions I’ve kept handy for my projects.  🙂

If you really want to save yourself time, Meshweaver Productions make two very extensive collections. For £82.48 GBP (about $125 USD), you can have hundreds (about 550, each rendered in multiple resolutions) of detailed nurnies in your library which represent hundred of hours of saved work.  The hatch I used is from their second collection of  of parts, many based on tank pieces.  (I don’t take compensation on this blog–I bought these myself and really, really like this product.)  

If you look back at part 5 of this series on Zbrush Mechanical, you’ll quickly be able to make fast alphas from your nurnies as well, expanding the possibilities for high quality detailing of your mechanical projects.

If you’re serious about mechanical modeling and surfacing, you owe it yourself to learn about nurnies and start collect your own parts for nurnification.