I recently made a custom PCB for the Plant Friends sensor nodes. The layout is based on the protoboard layout. The Moteino sits in the socket.
I'm planning to deploy a bunch of sensor nodes for my other plants and making my own custom board will make the task easier.
I also made a custom soil probe. Fearing that the eBay soil probes might contain lead, I had to design my own. Also, the eBay probes are corroding pretty badly after 6 months of use.
Here is my custom soil probe:
Here is a side by side comparison of my soil probe and the eBay one. You can see the eBay one looks pretty bad.
The gold plating should provide much more corrosion resistance. Only time will tell tho.