I wanted to purchase a mini fan for my mom while working in kitchen. Searched in the internet and found battery operated mini fans but air flow is very less. So I decided to make my own and came up with 2 approaches.

DC powered fan
AC powered fan

With DC powered fan, lot of circuit needs to be made (AC to DC converter, DC Step down, Speed control) and the DC motor heats up quickly. need to manage the heating issue, noisy, easy wear and tear.

With AC powered fan, less circuit or only speed control (optional) is required. AC fan doesn't heats up quickly and can be run for long time, less noise, less wear and tear.

I decided to make my own design using Panel cooling fan which has good airflow.

Note: Since this mini fan is powered with AC (high voltage) please be cautious while working.

Supplies

M5 Bolt 35mm - 1pc
M5 lock nut - 1pc
M5 Bolt 10mm - 4pcs
M4 Bolt 55mm - 2pcs
M4 Bolt 20mm - 2pcs
M4 lock nut - 4pcs
M3 Bolt 50mm - 1pc
M3 Bolt 30mm - 2pcs
Panel Cooling Fan (120 x 120 x 38mm) AC - 1pc
BT136 - 1pc
500k potentiometer - 1pc
10k resistor - 1pc
0.1uF 400v - 1pc
DB3 Diac - 1pc
AC power cord - 1pc
Perf board - 1pc
Zip tie - 1pc
Plastic mesh
3d printed parts

Step 1: 3d Printed Parts

Download stl files from printables.com

Base - 1pc
Electronics Cover - 1pc
Air Guard - 1pc
Tilt control - 1pc
Back cover 1 - 1pc
Back cover 2 - 1pc
Handle - 1pc
Handle spacer - 4pcs
Tilt Knob - 1pc
Tilt knob stopper - 1pc
Speed Control knob - 1pc

Step 2: Tilt Control Preparation

Insert two M3 screws inside Tilt control part as shown in pictures to give the part more strength.

Step 3: Top Part Assembly

Combine Tilt control and Air guard parts with four M5 screws.

Step 4: Tilt Knob Preparation

Insert M3 screw to Tilt Knob to give extra strength. This part is responsible for vertical alignment.

Step 5: Body Assembly

Assemble the body by combining Top and Base parts as shown in pictures. Place Tilt knob between two parts.

Step 6: Back Cover Assembly

Place plastic mesh between back cover 1 and Back Cover 2 and apply glue.

Step 7: Fan, Handle, Back Cover Assembly

Assemble the Fan with 2 M4 long screws and 2 M4 short screws at the bottom. Add Handle and back cover in the process. Do not miss to add handle spacers.

Step 8: Electronics

https://www.hackatronic.com/circuit-of-fan-regulator-based-on-triac-and-capacitor/

I have used the circuit which is available in above website. This is to control the fan speed. Circuit is made in perf board and pushed the circuit in base print. Added zip tie to power cord in order to prevent the wire to come out. Close the cover as shown in picture. Insert Speed control knob. 500k potentiometer is prone to electric shock, covered with speed control knob.

Note: Working with high voltage is dangerous. Power ON/OFF switch was not added in the design, please work carefully.