I've been working on a project that used a 16x2 LCD display and wanted a nice finish that also allowed me to seal against water and other liquids. I also needed impact resistance, low cost and the ability to be changed easily if worn or broken.
I considered many different ideas:-
1) A full sheet of perspex on the front of my enclosure. Great finish but expensive and difficult to seal as fully transparent.
2) A small piece of perspex over a cut hole in the enclosure. Cheaper but not so nice finish, showing the full LCD through and any rough enclosure cutting.
3) Looking for access to a laser cutter to make a profiled perspex window that sits through the enclosure hole to sit flush with surface. Difficult tolerances and no depth control with a laser.
4) Asking a local workshop to make a profiled perspex window on CNC milling machines. Cost more than using a full perspex sheet.
So, eventually I tried something else and ended up with what I think is a nice professional finish that is easy to do, cheap, and results in an iPhone type black glass frame style, with a clear window exactly the right size to show the display properly. It can also be easily adapted to any other type or size of display.
Step 1: Create and Print a Template
The first step was to take the existing display and get this transferred to some kind of CAD drawing, so that a template can be made.
Since I've been getting more proficient with CADSoft Eagle, I simply used a blank BRD file with mm grid to create my drawing and print at scale on to some card.
You could use any package that allows you to create accurate drawings at a 1:1 scale. You need it to come out in print to the correct scale.
I took the original dimensions of the 16x2 LCD display I had and drew it up, including the stand-off holes. I then added an additional 5mm surround to give my bezel additional strength around the fixing holes, and also to make it look better since the holes wouldn't be right on the edge.
Print the template off and then use a sharp knife (craft knife, trimming knife, scalpel), or scissors, to cut out the outline and the inside border.
I used plain card for this, but a bit of extra time to make a plastic/acrylic template might be better if you intend to make a lot of these.