The box with the parts from reichelt.de arrived today at the same time as my eBay order of a breadboard (came from the UK). Nice timing.

Searching my DIY stock I found a 600g bin of sodium persulfate that will come handy when it is time to etch my PCBs. 600g will be largely enough for the next few boards (it is mixed at a ratio of 1:5 with water). Since sodium persulfate works best at around 40-50°C (104-122°F), I have to find a solution for heating up the etching bath. Some people simply use an electric kettle and some tap water to mix water to >40°C which seems to be hot long enough for about one or two PCBs and will probably be my method of choice for the first few tries.

I would like to have a permanent heating option though with some kind of double-boiler to heat the etching solution to avoid the hassle of calculating and mixing hot fluids. I still have a few peltier elements lying around that I could throw into a design. Peltier elements are small pads that convert electricity into heat/cold - on eBay.com they start at 20$, on eBay.de they start at around 3€ =~ 5$. 

Since there is a large hardware store nearby that has a 3D printing facility, this sparks up a few ideas for a new project (read: 3D printed µC operated adjustable temperature controlled double-boiler etching bath using peltier elements - could probably be made for under 25$, at least with the cheap peltiers on eBay.de).

But lets not overdo it project-wise. Should I really go that far, it will certainly appear as a project here on hackaday ;) with STL files and the like so that other people can have their own one printed.

For now I'll do a bit of Arduino hacking and see to the CPLD boards in the next few days.