Step 1.  Machine the Front Panel

The enclosure is machined using standard milling and drilling operations.  Note that when cutting plastic, you should use a fairly high RPM and use a slow feed while drilling or use a wood block or something behind the front panel.  The enclosure is made of ABS plastic so use as fast an RPM as possible without melting the plastic.

None of the drill holes in the drawing are critical.  You can do fine using the closet nominal drill size that is greater than the called-out diameter.  For example, the 0.469 (12mm) diameter called out for the tact switch buttons can be drilled with a 1/2" diameter drill bit.  The overlay will cover up any overage or mistakes so don't worry about precision here.

For the display cut-outs, use an 1/8" or so end mill, either two or four flute.  The following figure is a dimensioned drawing of the front of the enclosure.

DRO-550 Front Panel Drawing (Click for PDF)