I’m looking for a prototype shield, that either has a rj45 connector or pads so I can solder on my own… but NOT an eithernet shield, I want to use the 8 pins for other purposes.
But put the rj45 jack in the same place as an eithernet shield, so I can use existing arduino cases with network jack cutouts.
You’ll have to look deep into the internet to find such a thing. I don’t think there is much of a market for it without actual ethernet functionality. I think you are better of taking any regular prototype shield that has that corner of the board free, and hack a breakout-board into/onto it:
I would cut out a square/rectangular hole from the shield to make the breakout-board fit flush in it. Then fix it to the shield by (super)glueing support perfboard on top and below of the flanges. If you are clever with a hacksaw you could even saw locking edges into the outside edge of the shield to prevent it from pulling out by force.
Another option might be to get a “dink and dent” ethernet shield from SF. (not sure if you can request something specific as this) You might be able to remove the components and check for (dis-)continuity and stick your own experimentation board onto it. Then jumperwire to the RJ45 pins, and other Arduino pin connector arrays .
I’ve already scoured eBay and Amazon, even a Google search. But nothing matching my description… I thought if I put the idea here, sparkfun might modify one of their Ethernet shields to match… Maybe…
The other option would be to take one of the prototype shields available in Eagle (or your cad package of choice) and modify it to add the RJ45. Should fit nicely on the $20-for-10 PCBs from ITEAD.