This is a table mat that would make sure your table is clean when you leave.

My desk is always messy, so I thought of a way to force myself to clean it before I leave. When I leave, I always take my phone with me, so the table mat works like this:

When I remove my phone from the platform, the table mat would check if I still have anything on the desk. If I do, the LED would light up. If I don't, it won't

Supplies

Wiring:

Arduino Leonardo

Breadboard

5 Photo Resistors

Male-to-male Jumper Wires

1 kΩ Resistors

Male-to-female Jumper Wires

Table Mat:

1 Plastic Table Mat (Whatever size you need)

1 Sheet of Nonwoven Fabric

Shoebox (or any kind of box)

Supplies:

Scissors

Paperclips

Utility knife

Step 1: Prepare the Table Mat

Place the plastic table mat on top of the nonwoven fabric. Secure both by using paper clips on three of the corners. Use scissors to cut the fabric to the same size as the plastic table mat.

Plan where you're going to place your objects on the table mat. For me, I only need my textbook, a mug for water, and my pencil case.

Step 2: Insert the Photoresistors

Put aside the plastic table mat.

Then, insert the photoresistors into the nonwoven fabric. Simply poke them right through the fabric where you're going to place your objects. Spread the legs of the photoresistors to secure them.

Step 3: Preparing the Platform

Take a shoe box and poke two holes on top using the utility knife. Insert a photoresistor in one of the hole, a LED in the other.

Cut a long rectangular opening on the side of the box using the utility knife.

Step 4: Wiring & Coding

Connect everything as shown in the picture:

For the photoresistors on the table mat, connect them to male-to-female jumper wires.

Then, put the breadboard and Arduino inside of the shoebox. The male-to-female jumper wires should go through the hole on the side. Finally, connect the male-to-female jumper wires to the breadboard.

For the photoresistor and LED on the platform, also use male-to-female jumper wires to connect them to the breadboard.

Here is the code.