I didn't create a shield. I just wired the RFM69HW transceiver to the GPIO pins directly. I used the following library which tells you which GPIO pins get wired to which ports on the transceiver. It does require some soldering but it isn't hard.
I used this same library to write a plug-in to my sensorReporter script but can't publish it because of licensing restrictions (sensorReporter is Apache 2.0, the RFM69 library is GPL 3.0 and the two are not compatible). But the code itself is really simple and easily reproducible. Or even better, etrombly has a whole Gateway published that works with the same Uber Home Automation Instructable code. In a fit of "not invented here" I wanted to make this part of ym sensorReporter rather than adopt these existing gateways largely because I wanted to hide things like node and network IDs and other hardware specific stuff from OH itself.
The example.py tells you pretty much everything you need to do to send and receive messages though if you want to forge your own.
On a side note, given updates I've done to my sensorReporter and the way in which it loads and works with libraries it is unclear whether the licensing problems are still a problem but sadly, better safe than sorry. Its ironic that a license intended to promote the publishing of open source code is preventing me from publishing my code on this.
Some lessons learned I have so far.
If you run in 915 MHz, while it will indeed work just fine with a 3" antenna, I did notice a drop in RSSI of about 10 when I dropped their lengths and the temperature of the gateway transceiver jumped about 40 degrees F. So if it isn't a problem, I'd make the antenna on the gateway plugged into the Pi be 6". You can coil it around a pencil to make it more compact.
You cannot lengthen an antenna by splicing a wire to it to lengthen it. My signal dropped to zero when I tried that.
I use a hollowed out pair of pieces of 2"x4" to house my first sensor. The wood in the 2"x4" is apparently a good enough insulator to drop the signal to unusable levels. So keep how you plan on housing it in mind and try to be flexible in placement of things so you can run the antenna out of the case if you need to.
I'm in the middle of building my second sensor, this one in a cardboard tube. I also paid better attention to the quality of the connections so maybe this one will work better. Grafana will tell me though.