ESP-03 is the smallest ESP8266 board that have on board antenna, it can fit for many projects that have limited space, such as wearable or portable device.

This instructables show how to build a testing board for early testing the ESP-03 board before actual soldering.

Step 1: Why Need Testing Board?

ESP-03 board is small, it is hard for soldering especially re-soldering if you want change pin connection while development
The pin interval is 2.0 mm, it is hard to match the 2.54 mm width bread board

Step 2: Preparation

a multipurpose PC board
2 x 7 pins male header
2 x 7 pins female header
3 x 10 k Ohm resistor
2 x button

Step 3: Bend and Solder the Header

bend both the 7 pins male header and adjust the interval width to around 2.0 mm
solder the bent header to the multipurpose PC board
stick a sponge tape in the middle for insulate between ESP board and PC board
cut the PC board extra part

Step 4: Fit the ESP-03 Board

Put the ESP-03 board on the PC board, check and adjust each header to make all can touch the ESP pin.

Step 5: Short the Reset Jumper

ESP-03 has a little jumper near Vcc pin, this is the jumper for connecting GPIO16 pin and reset pin. To facilitate the reset function for the testing board, it is required to short this jumper. Simply solder this jumper can make it.