How to Make Detailed Scale Models Using a 3D Printer

So you want to make something tiny, do you? And you want to make it look really nice?

So where do you start? Right in your own imagination. If you can imagine it, it can be built.

Imagination is a key to building something and successfully finding the tools you need to do it.

Supplies

As I said before, a good dose of imagination will help you a lot. Sewing, craft, and jewelry stores are good places to look for some of these things, but art stores and the makeup aisle may supply some of the others. Amazon and Ebay are always good places to look if you don't have a store nearby. As always, if you find a tool that looks like it might work better than something I suggest, don't be afraid to try using it. Any tool can be the right tool.

Pins, needles, nails, and wire

Brass rod and tubing

Small, sharp hobby knives (the sharper the better)

Small pliers (non-magnetic ones are nice)

Tiny drill bits and a pin vise (a tiny non powered drill)

Various glues (super glue works well, UV resin could be nice, epoxy gives you a long working time)

Paint brushes (all shapes and sizes)

Model or art paints (enamel is popular and is available in brighter colors, but acrylic is water cleanup)

Small screwdrivers

Sharp files in various sizes

Fine sandpaper

A jeweler's saw (and some very fine blades to go with it)

Tape, scissors, string etc.

And last but certainly not least, a 3D printer ;)

I have all of this stuff laying around because I've been collecting it as I needed it for quite awhile. I've never had to use all of it for any one project though. This list is meant to just be a place to start thinking of what you might need or could use. Depending on your project, you may need way more than what I have listed, or you might not need half of it.

Step 1: Design

Once you have figured out what to build, it's time to start designing. Or in my case to start measuring the real thing in order to reverse engineer it's shape and scale it down. I find it easiest to actually measure the thing instead of trying to design it just from pictures, though I have had to when all I had was pictures. Something to keep in mind as you are designing is that you don't have to design or print your model in one piece. Though it may be faster and easier to print in one piece, you usually won't get prints as crisp and clear. If you orient separate pieces on the printer's bed correctly, you can get very nice prints. A bit of knowledge about your printer will help here.

Your printer is limited by it's X, Y, and Z axis resolutions (or once you get up to bigger parts, the printer's bed size). The X and Y (left/right and forward/backward) axes resolutions are basically limited by the diameter of your nozzle (the smaller the nozzle, the finer the resolution). Most printers come with 0.4mm nozzles. I've heard of nozzles as small as 0.15mm (expensive and hard to find). My smallest is 0.2mm. The minimum Z axis resolution on many printers is 0.0437mm. As you can see, the Z axis should be much finer than the X and Y axes. But that's not always the case.

Say you were to print a pyramid. The first layer would be a square. But because the nozzle on the printer is round, you can't actually print a corner. The sharpest radius curve you can print then is the radius of the nozzle. Not a corner. Now, in order for the print to be a pyramid, the next layer must be the same shape but smaller than the first layer. So the sides of the print will have steps, or layers. They can't be smooth. So how do you make a good pyramid? The best way I know of is to print the part over sized and then use sandpaper or a file to make the sharp corners and flat sides.

What about a sphere, you say? Well, printers can't print a circle. They can print many sided polygons (without true corners). But not circles. And because it prints in layers, the Z axis also can't be a true curve. So you'll need more sandpaper. To be honest though, it will have to be bigger than about an inch before you start to notice that it's not a curve. And if you end up painting it, that hides some of the roughness too.

Now some talk about using support while printing. Printing programs like Cura or Repetier won't let you print with an overhanging angle (imagine that pyramid upside down) of greater than 45 or 50 degrees without support. Now take the sphere scenario. At the very bottom it's much greater than 50 degrees and would need support. Support won't give a nice smooth bottom layer like the build plate does. So I try to avoid using support. (To be fair here, I've never used dissolvable filaments. They might be able to give just as good a surface finish as the build plate does. You'll have to do your own research, or maybe someone can weigh in in the comments.) So how do you print it without support? You could split it into two hemispheres printed separately. Or if the part isn't critical, make the bottom flat enough that it doesn't need the support. Now it wouldn't be a true sphere then, but it wasn't a true sphere before anyway. And remember, it might not be how accurate you make something, but how good it looks when it's done. And this leads into my next part: scale of small parts.

If you look at either the fenders of my 1/87th scale tractor (this instructable's main picture), or the sides of my 1/64th scale grain wagon (above picture) they should look thin. To scale though, they would be about 2 inches thick in real life! (The real ones are thin sheet metal) But do they look good? I think so. If something is too small to be printed, you either have to make it big enough to be printed or forget it entirely.

So where am I going with all this? Well, that grain wagon above is made of 22 printed parts (plus 7 nails and 2 pieces of wire). If I had printed it as one piece, every angled section would've been made in steps and some would need support. By printing it in pieces, I could lay each piece flat. That way it has smooth surfaces. By printing separate pieces, I can also easily add moving parts. The wheels on this wagon roll and steer.

Step 2: Printing

I'll try to just brush over this subject since there are many more people out there who have already covered this topic. There are many variables in this step. Make sure you print bed is cleaned and leveled. Make sure the filament is dry (it absorbs moisture from the air). PLA filament will give you the best chance of smooth prints. Don't cheap out on filament! Your filament needs to be consistent if you want your print to be. If you use a normal 0.4mm nozzle you'll get nice prints and a short print time. From personal experience, I've used a 0.2mm nozzle, and when it works it gives incredible detail. But there's that key word: when. I had lots of problems trying to get the print to stick to the bed. And because the nozzle is smaller, an even smaller piece of gunk is capable of plugging the nozzle. Take what I've said with a grain of salt though. I wouldn't call myself a professional. When printing, don't put all your eggs in one basket. Don't try to print 50 things at once. Because if one starts to fail it could ruin your whole print. And if it does print fine, you'll have lots of stringing between each piece that you'll have to clean out later. One other note, the color filament you use may help if you plan on painting it later. For example, painting a piece of black plastic with white paint will take several coats of paint. Try to use a similar colored filament to the color paint you plan to use, if you can.

Step 3: Assembly and Painting

Now that all the parts are printed, you need to make them look good. Stringing, rough spots, edges that don't look good enough? Sharp knives, files, and sandpaper. Use glue to fill in any holes that are there (or you make accidentally). If you have any moving parts (wheels, etc.) now is the time to make sure they have smooth moving surfaces. I use small nails as axles and steering pivots. If you had any extremities that were too small to be printed, you can sometimes make them out of small brass rod or tubing. Now at this point you have to choose to either glue everything together and then paint it, or paint the individual pieces and then glue them. It is much easier to paint something a solid color than to paint half of it one color and half another color. Sometimes that can't be done. Then it's time to break out the tiny sharp paint brushes and try to paint a straight line. For small dots, sometimes a sharpened toothpick works well. If you try to match a paint color by mixing paints, make sure you keep track of how much of which colors you used. Also ,try to use the same mixed batch of paint for the entire project, because two batches of paint that are supposed to be the same color but aren't really show up.

Step 4: The Collection

Making small models is lots of fun. The 3D printer made it much easier to make stuff this small. Almost everything I've built has been 1/64th scale, a very common small scale for farm toys. These are just a few of the projects I've made or am currently working on.

Have fun Building!