Tinkercad is an amazing (and free!) online 3D modelling tool for all ages. By using simple geometric shapes you can create everything for cars to cats. However as my students pointed out, the end result never looks that natural…
So we experimented with Sculptris, a fantastic free ‘digital clay’ sculpting program. Scupltris is a great program for creating more organic models however creating the overall shape of your creature can be a challenge. Many students’ accidentally created comically misshapen creatures or odd protruding vertices. We tried importing our Tinkercad creations into Scupltris but the program couldn’t handle the files.
Meshmixer is a free program for preparing 3D models for printing and has a wide range of editing tools including a sculpting section.
The aim of this instructable is to show you how you can take a Tinkercad model and edit it in Meshmixer to get a more organic finish. If you want to learn more about using Meshmixer for further editing can I recommend trying the HoneyPoint3D Meshmixer course. I found it well laid out and it delves into some of Meshmixer's more powerful functionality.
A quick side note on computer ergonomics
3D modelling and sculpting tends to take a lot of time and involve a lot of fiddling. Please make sure that you start in a comfortable position where your arms are at pleasant angle (ideally 90 degrees). Also take regular breaks. You’ll be thankful for this once you have a 3D printed your creature and aren't complaining of back pain!
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Step 1: Exporting From Tinkercad and Importing Files Into Meshmixer
Step 2: Prepare Your Model for Sculpting
But wait, before you can sculpt your model you'll need to remesh it. Why, you ask? Check out these ugly shapes I get from the smooth tool (the first picture)! Yuck! That's triangular abomination instead of a beautiful soft fantasy creature. Let's remesh it fast!
First head to the Select section by clicking Select on the left side menu. Then click one part of your model.
To select your entire model press ctl + a on your keyboard. Then navigate to Edit… on the top of the menu and press remesh.
Step 3: Remeshing Options
So as you can see in the first image, Meshmixer has remeshed the creature and it looks…jagged.. Not only that but it's claws are all but gone!
So to check what's going on press W to see the wireframe. Here we see that Meshmixer has created hundreds of tiny triangles to cover the creature. This would probably smooth well but you may want to try another re-mesh mode to get a more accurate model. So let's use the 'Linear Subdivision' mode (Remesh Mode can be found at the top of the Remesh menu). Here we can see a much more accurate remesh where Meshmixer has simply sub-divided all the original faces. Notice how the creatures claws, horns and beak are sharp and crisp. This mode should be useful for models that have crisp edges.
Step 4: Controlling the Size and Strength of Your Brush
Time to navigate to the Sculpt menu (which can be found just under the Select menu button). Press the Brushes button on the side to get the a look at all the brushes available to you.
But first let's have a quick look at your brush options. Press space bar to get a 'quick menu' for brushes. Here you can control the size and strength of your brush (as well as a few other colour and mesh options). This is very useful for when your sculpting because you can see the size of your brush change while you're adjusting it unlike if you change your brush size from the left menu were you'll need to keep moving you cursor off to see the actual brush size.
Step 5: Start With the Smooth Brush
The best way to learn how to use all the brushes in Meshmixer is to experiment with them. A great place to start is with a smooth brush.
To use simply press the BubbleSmooth brush and move your cursor over the parts of your model you want to smooth.
In this picture I've smoothed the left-hand side of the creature. As you can see, the wombat creature now looks a lot less like Lego construction and more like a fantasy pet…mostly!
Step 6: Try the Draw Brush for Filling in Gaps
To create the creatures body I used three spheres in Tinkercad. Although they gave a good approximation of a wombats back it'd be nice if it looked a lot smoother so I'm going to fill in the gaps using a draw brush.
To begin with, grab a draw bush from the menu. I used the Draw2 brush. Then just fill in the gaps as you see fit. Don't worry about the model look messy at this stage, just fill in the gaps and give yourself enough material to work with.
Now use a smooth brush to smooth it all down. I used the RobustSmooth brush.
Step 7: Finishing Up and Preparing Your Model for Print: Overhangs and Generating Support
Now it's time to prepare you model for printing! Head to the Analysis section which can be found in the left-hand menu under Edit. Here you will see a range of tools to help you analyse your print. For now click on the Overhangs button.
When you open the Overhangs section Meshmixer will highlight the parts of your model that will need support in blue.
Click the  Generate Support button near the bottom of the section. You can choose to use Meshmixer's supports over those generated by your regular printer software if you wish however I usually use this as a way of seeing what parts of my model need supports. I may then choose to edit parts of your model to make it more 'printer friendly'.
Step 8: Conclusion
Tinkercad is a brilliant program for getting a solid 3D model 'base'. Combined with Meshmixer your ability to make organic looking creatures is endless! Both are powerful programs and I'd highly recommend just playing around with both to see what results you can get.
To my students, now with a little bit of work that cat you made in Tinkercad will look like a cat, so keep practicing your sculpting!