Step 1
First, remove the protective sheet. The sheet can be removed by carefully using your nails. It is also possible to submerge the sheet in water for about a minute first to make removal easier.
Fasten the spacers to the bottom plate using the M3-5mm screws.
Step 2
Insert the two side plates into the bottom plate.
Step 3
Fasten the front and back plates using the M3-10mm screws and nuts. If the nuts are hard to insert, rotate them carefully until they fit, do not force. Also, take care when inserting the screws, go slowly and be careful against overtightening. Slowly tightening and loosening the screw should make it easier to fasten.
Step 4
Insert the Arduino board and fasten it using the M3-5mm screws.
For UNO R2/R3 skip the screw closest to the reset switch: The upper left screw hole is very close to the header.
If you need the extra mechanical stability of the fourth screw, it is possible to use a wire cutter to slice off a small portion of the head of the screw and then insert it.
Step 5
To insert the top plate, tilt it slightly and insert the two protruding parts into the holes on the back plate. Carefully press your fingers against the left side of the plate and press down to fasten it completely.