Editor's note: Paul Benson is the artist behind The Droid Foundry, a series of fantastic robotic themed sculptures designed in Tinkercad. He recently wrote about his process for designing, printing, and painting his creations and graciously allowed us to compile them for this blog post.
The following notes have been written in the hope it may help folks who are interested in designing their own droids/robots or anything else for that matter. Of course there are different methods for this process but this is how I do it.
Step 1: The Design Process
I use Tinkercad which is a free, online 3D modelling program that runs in a web browser, known for its simplicity and ease of use. The program uses a simplified constructive solid geometry method for constructing models.
On the ‘workplane’ primitive shapes are combined together as either ‘solids’ or ‘holes’ to create new shapes. Tutorials are available to get you started.
I could use something more complex, but Tinkercad does the job.
In addition to the standard library of primitive shapes that is available, you can create custom shape generators using a built-in editor. There are also a whole range of ready made community made shape generators available. I would advise the use of high resolution shapes such as a cylinder and sphere to produce the best prints.
I often use parts from previous models to speed things up. It is just a matter of disassembling a model then copy and pasting parts onto the workplace for the model I am working on. For models made of more than one part it is always a good idea to do a virtual fit, to make sure the design works and the parts actually do fit together.
Step 2: Preparation for Printing
Models then need to be downloaded for printing, this can be done from the Tinkercad dashboard by clicking on the saved model and then selecting download as an STL file.
From experience I have found that complex shapes made up of lots of parts do not always download successfully. To rectify this click on ‘shape collection’ and then ‘create shape’. Transfer the model back to a blank workplane and then download that file.
From there I upload the STL file to the website of 3D printing company. Of course your model could just as well be downloaded to be set up for a home printer.
In order to prepare for uploading to 3D printing company, to make printing economical, the individual parts are grouped together to occupy the smallest volume in the machine.
Step 3: Preparation for Painting
After the model is printed by selective laser sintering I receive back from the 3D printing firm. It arrives dyed black as this suits the weathering process I use where the colour will show through as paint chips and rubbed or abraded areas later.
Nevertheless I also prime with a matte back acrylic aerosol paint as this does provide a better surface for subsequent painting.
Step 4: Painting
When the primer coat is dry, next comes the hairspray and salt crystals. The salt crystals will be removed later and will leave realistic paints chips and wear in the final paint layer.
Cheaper hairsprays as better for this job as they tend to be more soluble later. So spray the piece with the hairspray and whilst it is still wet I sprinkle salt from a grinder containing salt crystals.
Sometimes I spray again to help to keep the salt crystals in place. How much depends on how much weathering you want to show, sometimes nothing at all if I want to show no paint chipping but just a bit of wear and tear on edges. In the image salt crystals are there on the body but not on the legs.
When the hairspray has dried I apply the top colour. Again I tend to use acrylic spray can paints which can be actual modeller’s paints, car priming paints or graffiti paints. The weathering does work with gloss paints but certainly works better with matte finishes. I always try to aim for the minimum number of coats necessary to ensure coverage.
Again I tend to use acrylic spray can paints which can be actual modeller’s paints, car priming paints or graffiti paints. The weathering does work with gloss paints but certainly works better with mattefinishes. I always try to aim for the minimum number of coats necessary to ensure coverage, but not obscure detail.
Step 5: Additional Painting and Weathering
Next comes the best part. After allowing the top coat to dry for a couple of hours I usually drop the model in warm/hot water for about 5 minutes, which allows for the salt crystals to start to dissolve. Then using something like an old tooth brush or kitchen scouring pad I work over the piece helping to remove the salt crystals, but also rubbing at edges and raised features to create the wear and abraded edges.
Obviously it takes a little judgment on how much weathering you end up and care needs to be taken not to remove the undercoat as well, although this can be corrected later by replacing the right colour with a paint brush.
The next stage is painting in details. I use acrylic paint bought in small bottles.
On with the weathering, by dirtying up with a dark brown ink wash. Dilute dark brown paint can be used. The ink goes into crevices and helps to define detail but on flat surfaces it acts as a filter and shows a bit of grime. After applying the ink wash with a brush I adjust the effect with absorbent paper, wiping down where I don’t want it to be too thick or dabbing to add a bit of variation.
To get the rust I use new and old rust weathering powders. Tamiya, MIG and Humbrol make these and are quite easy to get hold of. They can be used mixed with water as a wash or applied dry with a brush. Apply where you want rust and then adjust again with absorbent paper, wiping away to leave in crevices or on flat surfaces as a filter. Mixed with water they can be used like paint as well and rust runs and trails can by applied with a fine brush.
I apply any numbers, logo etc. as dry rub transfers. Graffiti tags might be added freely drown with a very fine waterproof ink pen.