This is a customizable stand for smartphones, small tablets, calculators, or other thin devices.
If you want, you can configure it to have holes for routing a USB cable, so you can use the stand while charging your device, assuming it has its USB port exactly in the middle of the bottom (which seems to be quite standard these days).
There is also an option to make it wall-mountable, although this will only really be feasible for smaller devices.
To create your own model, hit the Customizer button, or if the online Customizer is broken, look at my instructions for running Customizer on your own computer. (Download both the .scad and .json file to get presets for the example models.)
You will need to set the ‘lift’ value high enough to have enough room inside the holder to route a cable through the optional front or rear hole. This depends on the type of cable. I recommend the flat kind of USB cable as can be seen in the photos: it is very flexible, the plugs are also quite small and fit through the holes easily. (Routing thicker cables with larger plugs through the rear hole may still be possible by first inserting the plug from above, and then inserting it again from below and then straightening the cable.)
You may enable the ‘preview’ checkbox to view the model in an upright pose while configuring it. However, do not print it in this orientation! It would require supports that can be easily avoided in the sideways position (and it would also look worse, and be weaker).
Before printing the entire model, you should verify whether your phone will really fit without having too much margin. To do this, enable the ‘testPiece’ option and set the width to 5. This will produce a quick-to-print slice of the stand, which you can use to check if you don't need to increase or decrease the ‘thick’ value, or increase the ‘lift’ value to offer more room for a cable.
This prints easily without supports if you did not enable the front or rear bottom holes. If they are enabled, you can still print without supports, but the holes may be a bit messy. It helps a lot to apply enough cooling while the upper part of the holes is being printed. It also helps to reduce layer height around this zone (if you can change layer height in specific parts of the print). Of course you can just print it any way you like, and if there is a bit of a mess in the holes, just cut it off with an Xacto knife. Supports can help avoid this, but will greatly increase print time and required material, for only a small benefit.
Due to the small contact surface, a brim or raft may be recommended especially when using more warp-prone filaments like ABS.
If you wonder what causes the stripes on the photos of my print, it is indeed the variable layer height: the silver filament I used looks slightly darker where the layers are thinner.
A few stick-on rubber feet will help to keep the holder from shifting around.