Tips for using plastic switch plates (via Ponoko)

[TD22057]

I'm getting ready to build a new custom keyboard (layout below) and was considering using a completely plastic (acrylic) switch plate and case made at Ponoko.  I'm thinking a 1.5mm switch plate (and top), two 3mm spacers, and a 3mm bottom plate.  Each hand will be separate (2 separate cases).  The switches (MX browns) have plastic posts that are 6mm from the bottom of the plate they clip in so every switch would rest against the bottom plate which should eliminate any flexing. 

I've only ever made plates out of steel before so some of the things I'm concerned about are:

• material thickness consistency.  Ponoko says +/- 10% which seems like a lot of variation.  I'm hoping that two smaller half keyboards will have less variation than a full keyboard so hopefully I can ignore this.  It's not a huge problem if the spacers are too thick, but if they're too thin, I'll have to sand down the keycap posts to get the case to work.
• laser kerf.  Cherry says the holes should be 0.551"+/-0.002" and Ponoko lists the laser kerf as 0.008" but that was measured 5+ years ago so I'm not sure I trust that.  I'm thinking about using holes that are 0.547" which would allow a kerf of 0.002"-0.006" and still meet the Cherry spec.
• top plate thickness.  Another option would be to use a 4.5mm top plate for thickness and a single 3mm spacer.  This might be cheaper but the switches won't clip in so I'd be relying on friction only.  I'd also assume that cutting accuracy (mostly via a thinner kerf) for the switch holes is going to be better in the thin material since it can be cut at a faster speed.

I'd like to hear any advice people have about using plastic switch plates or laser cutting from Ponoko.

Thanks, TD

[TD22057]

I went ahead and designed a plastic case with a 3 mm base plate (clear acrylic), two 3 mm spacers (black acrylic), a 1.5 mm switch plate (black acrylic), and a 3 mm top plate (walnut veneer).  The walnut veneer is expensive and I'm building two keyboards so the total bill was going to be about $130.  I decided a prototype was probably a good idea so I had ponoko cut half of once case out of cardboard (for about $20 delivered).  Everything looks good - the layers are thicker than the plastic will be but the switches fit snugly and there is room for a teensy in the corner.  I may tighten up the spacing on the top plate but other than that I thing my design is looking pretty good.

I'll post a full build thread when I get everything put together and hopefully answer my own original questions at the same time (assuming my sizing all works out).  Now if I could just find the missing DSA retro caps I need...

[TD22057]

My ponoko order came in today, it looks fantastic, and everything seems to fit nicely.  I'll start a new thread w/ a full build log and include the design files for anyone who wants them but here's a preview (final screws will be painted black).

[suicidal_orange]

Looking good, I hope your wiring is pretty given it will be on display