This article was originally published on Turtle Rover website blog (back when Leo Rover was Turtle) and the photos and some descriptions may be outdated. The tips and ideas remained the same, though, so I decided to keep the article in the original.

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Most artists are not engineers, and most engineers are not artists. Once in a while you need to make your hardware project just ‘look nice’ and this is when you should be both of them.

Here are 4 tips to make your design look and feel better!

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1. Round corners like a pro!

Our brain doesn’t like sharp corners. It makes the visual experience more alerting rather than calm and aesthetic. And it’s Apple who accustomed us to the feature and made the design look more eye-friendly. If you use any 3D modeling software, you can see there’s a huge difference regarding the parameter you enter when rounding the element corners.

Now, take a look at the corner mathematics. There’s one extremely important thing to remember: keep all the widths around the corners equal. You could easily spoil the design not being careful with the corner radii.

I used the rule when designing Turtle’s ‘face’. As I implemented several lines to the design, I needed to keep them separated by an equal distance every time I rounded them. It’s easy to remember that every radius needs to be increased by the clearance distance.

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2. Keep all distances as low as possible

The more compact design, the better. You can use it as a rule of thumb.

It’s easy to add any new elements and features to your design, but you should always be careful when changing its outline size. Remember to cut down every millimeter of unnecessary dimensions. Trust me, everyone loves to see ‘compact’ products.

When I first designed the rover's chassis, it was way out of the scale. Had a lot of trouble decreasing its wheel width and the rover's height, but finally, managed to cut unnecessary millimeters of the body and ended up with ca. 24 mm lower outline. Remember not to be tempted to add too much clearances and material thickness just because you are afraid of the further manufacturing. Try it, test it, and then implement it or not — final design needs to look final.

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3. Choose either ‘seamless’ or exaggerate the seams

Everyone is into ‘seamless’ engineering, but not everyone succeeds in producing such features.

Apple ‘re-invented’ the word showing us products which seem to be made out of one piece of aluminum. But the way to there is long and full of darkness.

You should carefully think if you (using either 3D printing or injection molding) are able to provide tolerances of both dimensions and shapes going down to a thickness of a paper sheet. If not, try to exaggerate the seam, leave 1–3 mm of space between the parts and/or round and chamfer the edges. It will give the design a noticeable connection line, but it’s always better to fully show where the parts are joined rather than to fail trying to hide it.

The same rule works for colors of two joined parts. If you can’t make sure the parts are the same shade of white, make sure to plan the elements to be contrasting. Try even using the colors from the opposite sides of the palette.

In Turtle, we joined two materials of different type, color and manufacturing process. The central strip of the case is actually a part of the rover frame made of laser-cut and bent aluminum. The sides are made of thermoformed plastic sheet. There’s no way these two materials would fit seamlessly — we decided to separate them with a 2 mm clearance and use different colors.

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4. Learn where to chamfer, and where to fillet and round.

We love to play with our product's edges, especially while working with CAD software. Although you can freely cut them, round them and complex the outline, remember the process may have an opposite impact on the final product feeling.

There are no chamfers in the natural environment, period.

Chamfering gives the design a more human-ish feeling. Use it everywhere you want to tell the user your product is a piece of serious hardware. The feature is commonly used for milled parts where the cutting tool leaves sharp edges and where, opposite to injection molding, there’s no need for rounding the edges for the process. This is why more slanted design will be considered quality and top-shelf, but still heavier and harsh.

Fillets and rounds, on the other hand, are used to provide more organic feeling. You’ll round the edges for injection molding and casting, but not only there. When it comes to 3D printing, most makers forget about rounding the edges and, as we are accustomed to molded plastics, there’s something odd seeing a plastic item with a sharp outline. Try to think how the part would be processed originally and what the limits of the process are.

Wheels of the rover are made of CNC-machined aluminum with molded plastic rims. This means we needed to cope not only with manufacturing and joining process of two different materials, but as well needed to introduce a design that would fit them both.

I decided to implement a cyborg-style design — connect organic round shapes to sharp-edged machined elements. The same way was introduced to Turtle's robotic arm to make it look more ‘natural’.

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Knowing the tips you should end up with a better looking design both in 3D-printed and CNC-machined parts. Hope it helps you during your own projects. Cheers!