Dave M wrote:

Anyone have experience in accurately cutting 1/8" thick acrylic Plexiglas
(Perspex) for LED displays?

Real Plexiglas normally cannot be sheared. it can be scored with a special
knife and snapped off like glass cutting. It can also be machined with a
router or mill. Just be sure the cutter is super sharp and keep the tool
moving fast. Cutting slowly leads to heat build up and melting.
I need to make filters for some panel meters of my own design, but am
having trouble finding off-the-shelf bezels and filters of the sizes I
need. Before everyone tells me that there are cheap Chinese panel meters
available
on the web, I already know about them. My meters are for a unique
application and the available digital panel meters can't be modified to
fill
my needs. The display is the really unique part, and I need to make my
own filters for the displays. I need 3 different sizes; 1.25" x 2.5".
2.75" x 5" and 4" x 5".

I've thought about using a table saw with a cabinet-grade finishing blade.
That's possible, but somewhat dangerous due to the small size of the
filters.
Also thought about hot wire cutting. That's quite possible, relatively
safe (just have to keep fingers off the hot wire).
I do NOT think you can hot wire-cut acrylic. It will make a LOT of fumes
and cut very slow. Acrylic has a pretty high melting point.

Might be hard to keep
the wire taut enough to make straight cuts, and guiding the plastic
through the wire or the wire through the plastic.
Also thought about cutting on a drill press or milling machine. Again, a
bit dangerous due to the small size of the work. Clamping would be
tricky.
Just rectangles? Why would clamping be tricky? If making a lot, you clamp
a sheet by the edges, and rout out the pieces, leaving a little space
between parts.

My scheme, if really setting up to make a bunch, would be to set up a fence
on the table saw and cut a bunch of strips the length of the Plexi sheets to
match one of your dimensions. Then, stacking a bunch of these strips, cut
the other dimension. That would make a lot of parts quickly.

If you need highly accurate dimensions, then the mill is the way to go.

Jon