The Merica 3 Inch uses very similar center frame geometry compared to our Merica 5 Inch. It uses the exact same canopy as the Merica 5 Inch. What differs is the arm and motor fastener design. Since there are so many similarities between the two craft you can use the Merica 5 Inch assembly manual. Just take note of the special provisions below.

Merica 5 Inch Assembly Manual 

Merica 3 Inch Bill of Material

  1. Top plate: The top plate is 2mm compared to 3mm on the Merica 5". It also uses slightly different geometry. This will not affect the build process. The steps are identical. 
  2. Bottom plate: The bottom plate uses slightly different geometry. This will not affect the build process. The steps are identical. 
  3. Arm spacers: The arm spacers are 5.5mm total thickness instead of the 4mm included with the Merica 5". Stack the spacers using a 2.5mm and 3mm spacer under each arm.
  4. Motor / Arm Brace Mounting Screws: The Merica 3 Inch motor pad is designed for only M2 screws existing on a 12mm circle. You should install the included arm brace only on the front two arms. Use the included M2 x 10mm screws and M2 washers to mount the arm brace and front motors. Use the M2 X 6mm screws that came with your motor and M2 washers that came in the frame kit to mount the rear motors to the rear arms. Be cognizant of how much of the screw is extending into the bottom of your motor. Use M2 washers as needed to achieve the proper amount of thread engagement into the motor.