This is a guide to build a Smartphone Dock with four USB inputs, an HDMI output and a USB C passtrough for charging.

With it, you can connect your phone to a TV or a monitor, as well as to many different types of USB devices such as keyboards, mouses, flash drives, etc, all while its battery recharges. The possibilities are almost endless.

Step 1: MATERIALS AND EQUIPMENT

USB type C to HDMI/USB3.0 adapter
Multiport USB hub
USB devices (m/k, flash drive, gamepad)
A smartphone with a USB type C port compatible with HDMI Alt Mode (you can search online if your phone meets the requirements)
USB type C cable and wall adapter
Cardboard
Box Cutter
Hot glue gun
Scissors
Tape
Superglue
Ruler
Pencil

Step 2: DESIGN AND ARRANGEMENT

The initial step consists in designing and assembling the cardboard shell that will house all the components of the dock. Depending on the adapter and USB hub that you've found, the shell might vary in shape or size, also being a factor how big your phone happens to be. We've provided some basic sketches to use as guides to design your shell, but feel free to change them as you like. While you're drafting the shape of the plates, make sure to leave enough room for the connection ports, as to not find any problems when fitting the inner components. If there happens to be any slight misfits you find while cutting the cardboard shapes, you may be able to fix them by sanding the edges.

The inner components should be arranged as to occupy the least space possible. As shown in the pictures above, all connections but the male type C should face the back or sides of the dock. The USB type C used for charging must face up in the front so it can be connected to your device while it rests on the dock.

Step 3: ASSEMBLY

After designing and cutting all the pieces necessary, you may start assembling the dock. Your main tools will be a hot glue gun, the tip of a pencil to spread the glue evenly, tape and maybe a bit of superglue.

There isn't much to explain in this step, as it is very dependent on the way you designed the shell. As a general tip, one should always start gluing the base of the dock to the components as to provide a general guideline of where everything should go. After that, you should start gluing together the side plate with the most amount of USB ports (our design had all of the ports on the left side of the dock). Apart from gluing the edges together, try to fill any seams and gaps you suspect may compromise the structural integrity of the dock with all the glue necessary, as doing so will be very difficult after closing the shell. After gluing said side plate, start with the front and back plates (remember to fill up the weak spots) and at last, finish up by gluing the last side plate, being very cautious as to glue it evenly. After completely sealing up the shell, glue the small bumps to the front plate to help support the phone.

Step 4: TEST THE CONNECTIONS

Before continuing to the next step, you should first test if all the connections work well, just in case any were damaged during the prior assembly.

Test if the phone can charge and connect through HDMI and USB. Apart from damage, you should test the USB hub you installed by saturating the connections to check how much voltage it can give out on each port. Our hub wasn't so successful in this test, as we couldn't connect devices that sucked that much power such as a light up mouse and keyboard, but with simpler devices like flash drives and a basic keyboard the dock performed pretty well.

Step 5: DOWNLOAD AND SET UP MACRODROID

For the final step, you must set up some behaviors your device. To do so, we suggest using Macrodroid.

Macrodroid is an app that can detect "triggers" such as charging, connecting to a network or moving the gyroscope of your Android device to perform actions you can configure with ease. We used it to switch the device's screen to landscape mode and to dim it, as it does not perform these actions automatically when connecting to a display. The ideal trigger would be an NFC tag if your device supports it, but as we couldn't find one, we simply configured it to detect if the device is charging (remember that the dock charges your phone). The actions we configured were the following: Force screen rotation forcing the screen to landscape, Keep device awake so it doesn't turn off, and Brightness (0%) to dim the screen. We made a second macro that detects when it stops charging to revert all settings to normal.

Step 6: FINAL PRODUCT

After building the dock and setting up our phone, we're left with a dock that lets us easily connect our phones to an external display and also a plethora of USB devices like mouse, keyboard, flash drives and more, enabling it to work as a media center, a videogame console or even a working station to edit documents, all using just your phone.