I just uploaded some pics on instructables but rejected cause there are not enough documentation.
i'm Korean so editing documentation in English is some hard. and So busy long times.
now i re-publish this.
there are very Thin copper plate in train model shop(or other model shop,.. anyway)
about 0.001~0.003" are good. I used 0.001 and 0.002.
Step 1: Toner Transfer
but you must STICK KAPTON TAPE BEFORE ETCHING.
after etched, you can solder like normal PCB
The most important part, is to adhere tightly the copper plate and tape here.
If you miss small gap between tape and copper sheet,
there will be etching acid and copper sheet cannot protected.
Step 2: Result
while do something i forgot this so it takes about 3 hours.,
the pattern is almost gone but not 100%.
so i wired LEDs and power. and it's glowing!