Parts you need to build the y-axis:
First take two 25mm x 5mm washers and place them on a 19mm x 5mm x 6mm bearing.
Repeat the first step.
Take Part_Y_1 and insert the first bearing with the washers.
Fixate all by using a M5 x 20 screw and a nut.
Insert the second bearing with washers.
Fixate everything with a M5 x 20mm screw and a nut.
Put the linear bearings LM8UU into the holes. This might need a little bit of force. Use a hammer to get them in.
Put the toothed belt pulley onto the stepper motor and fixate it.
Insert the stepper motor.
Keep it in place by using 4 M3 x 20mm screws.
Insert GT2 belt like the red arrow.
Take the shaft and place it as shown in the picture below. Use Part_Y_2.
Fixate everything as shown in steps 12-15.
Put Part_Y_1 on the linear steel shafts.
Use Part_Y_3 and fixate it just like Part_Y_2 above.
Insert the belt in Part_Y_3 and fixate it by putting Part_Y_5 in.
To tension the Belt use Part_Y_4 and 2 M3 x 30mm screws.
Mount to whole y-axis on the Ikea Malm chest by using 12 M3 x 30mm screws. You need to drill some holes first.
Repeat all steps and use the mirrored parts.