A Raspberry Pi single-board computer can be easily transformed into a wide range of devices, including a wireless hotspot. You can use the on-board Wi-Fi chip or an external USB Wi-Fi dongle compatible with Raspberry Pi and use the device as a portable wireless hotspot. All you need to do is connect the Ethernet cable and supply the power. The Raspberry Pi starts the hotspot automatically on boot.
How to Make a Raspberry Pi WPA Encrypted Wireless Hotspot Device