I'll try moving the lightsource further away, it's about an inch or so away, less along the edges. The bulbs are fluorescent, two at the top and two angled on the sides, I'm using this, it has 4 9-watt bulbs:
http://www.amazon.com/Salon-Edge-Acrylic-Shellac-Curing/dp/B006QO4BRMthe board is sandwiched to the transparencies with glass, I'm using a 5 x 7 picture frame with a spring loaded cardboard back so it keeps them sandwiched pretty well. The transparencies are pretty good, with three stacked I can only see one small speck of light on the ground plane when held up to a bright light source. They were printed by a local printshop on laser printers.
The board looks perfect after developing, it's only near the end of etching that the pinhoels/pitting happens.
Well done.
Now, the question we all really want to know,
What is it?
Hah, get ready for a bit of a read.
I designed and am trying to make a new instrument cluster for my car (1986 Saab 900), making all the gauges and everything myself so it fits in the stock housing.
This board is the front of the tachometer, the outer ring holds 24 WS2812B RGB LEDs (Adafruit Neopixels), the inner has 16 for either a clock or boost/vac gauge, have not decided yet. The other pads near the leds are for 0805 decoupling capacitors.
Each gauge was designed to have a small AVR powering it so I can change their function whenever I wish, all the gauges communicate via i2c to a "master" atmega328 hooked to a 20x4 LCD screen so I can have exact readings from sensors.
Each gauge is made of a "stack" that plugs into eachother, so it's somewhat modular and if I want to change something I don't have to redesign the whole thing, just one of the three plates. First plate is the display portion, second is the AVR, oscillator, ISP header and the third is the input.
For the tachometer the input plate consists of an R/C filter, optocoupler, schmitt trigger and a few other components to convert the 12v NOISY square wave into a clean 5v signal to trigger an interrupt on the AVR.
I figured it would be a good first real project. Not dead simple, but complicated enough that it's still a challenge. I've had to learn quite a bit to get it all to work, totally worth it.