Introduction

Everything was going nice with my custom Arduboy, after painting the PCB with a sharpie marker, I just need to reattach the LCD and paint the buttons with a shiny gold color. 

All the other Arduboys are looking how the gold paint gets dry. But the paint never got dry:

Now I have no buttons. The paint melted a layer of the coating and I had to discard them.

Design

A and B buttons

These are quite simple. Copying the dimensions from the original ones I get a simple profile:

 Then you have to revolve the profile around the right side vertical axis and you get a nice button:

Directional buttons

These are more complex because the shape is not a primitive. My first design is composed by two simple shapes and several fillets:

Using freeforms, I can replace the top part with a more organic shape:

Done. The directional button is ready.

Problems 

So, it seems like my printer saved the Arduboy. Now I can assemble the console and play... right?

After few seconds I notice that the buttons are crap. You have to press them extremely hard to get a key-press registered. Something is wrong. The only difference with the original ones is a protrusion in the bottom. Of course, I cannot make that protrusion because FDM 3D printing limitations.

I printed so many versions trying to achieve that protrusion... nothing worked.

Sometimes you need to think out of the box, what if I did not print that protrusion but used filament for creating what I needed:

A piece of filament goes sideways (to use the constant diameter of the filament to my advantage)  in a hole, below each button. 

Conclusions

After playing for several days with them, I can say that the new buttons are perfect. And since you cannot buy button replacements, there is no really another way to fix your Arduboy. 

I cannot perceive any difference between the printed buttons and the original ones just by touching them. But I am printing them at 0.05 layer so the finishing surface is really smooth on the fingertips, so maybe that is the reason.