more notes:
I just replicated the input PCB for the Keithley 228 Source Meter in EasyEda.com (its public so check it out) and ordered the boards from JLCPCB.com. Just $2 for 10 boards with "gold fingers" (card edge board) and DHL was about $19USD. They should be here within a couple days. I also ordered a couple SMD breakouts with stencil that are here now. I'll post a video about it (hopefully) tomorrow.
If you have several boards in your cart, you can get the 1st batch of, up to 10, PCB's for just $2, then each batch of PCBS thereafter is just $5. IMHO, its well worth it to send 3-4 gerbers in one order and get them all shipped at the same time, for the ~19USD flat rate. You can also get free shipping if you order the BOM via LCSC.com, their parts store, during promotion periods.
The default QTY is always 5, but if the board is small (less than 100x100) you can usually get 10 for the same price. Also gold fingers are free (just learned this one). You can "panelize" small PCBS yourself and still get them for $2. I did this with the SMD breakouts.
The solder mask layer is automatically generated, and not an option in the layers tool. So we cannot alter it to, lets say, leave a guard trace exposed. I am looking into this more now. I used the "pads tool" (adjusted in the sub-menu) to get exposed copper tracks and it worked well.