playfield overlay thoughts

So the question was brought up, what's the best way to do the playfield art.  While I haven't actually yet installed my high speed vinyl overlay, I figured it anything I did was better than the condition it's in now.  However, there is the nightmare of getting the cutouts of the inserts lined up.  I've printed small sections of space shuttle to touch up my existing playfield with 8x10 stickers, and even that's a nightmare to deal with.  Also after reading a recent thread on pinside about planetary pinball selling overlays (and people talking about how CNC cutouts varied during production), it makes me second guess myself.

Now when I worked at a company that built OEM chargers for other companies, we did decals for multiple customers all the time using the same plastic housing.  One thing I learned to avoid manufacturing error was to have about 1mm overlap of LED windows.  Let's say in the plastic case you had a 6 x 10mm viewing window where the LED shined through, that would mean the clear window was 4 x 8mm.  That way, even if the window was slightly off, you would never see the edge of the hole in the case.

Now inserts actually sort of suck on their own (exposed).  They swell, they raise out of their holes, they cup, they crack.  They also make printing rather hard to line-up.  Mylar has been brought up, it's even been used.  Mylar however is still very thin, usually .010" (compared to say .004" for paper or vinyl).  I'm starting to toy with the idea of printing a semi-transparent inside window decal.  Think car window sticker, think the decals that are on the bottom of pinball plastic ramps like earthshaker or elvira.  Now imagine instead of a decal being applied to the playfield, you simply apply it to a sheet of thin acrylic plexiglass (1/16") with a sticker pre-applied underneath.  This gives you several advantages:
1. You have complete freedom to get it aligned.  Because it's so thick, you can literally line it up with a couple screws, then hold it down with playfield posts alone.
2. You will never wear down to the artwork, ever.  Plexiglass is super tough, and if it does get worn or fogged up, it can be flame polished.
3. There's no need to separately print waterslide decals (that don't stay on very well) onto each insert, it can be pre-printed on the decal already.
4. Since most store wood is just under 1/2" (and playfield wood is normally 17/32"), this extra thickness will help make up the difference.

So basically you get a clear PET vinyl decal, like this (but reverse the image since it will be backwards):

From a place like bannerbuzz for $29:
http://www.bannerbuzz.com/clear-window-decals.html

Order a sheet of acrylic for $18:
http://www.estreetplastics.com/Acrylic_plexiglass_sheet_s/182.htm

Use soapy water to apply the decal to ensure there are no bubbles (like installing window tint), then install it on your blank playfield.

Also the thicker acrylic sheet is more likely to keep the inserts flush vs mylar (I have a whirlwind that's holding up, but you can feel a slight hump on a couple of them).  This will ensure smooth play for many years.