I have an ESP8266 with OLED display from Heltec-Aaron-Lee called the WifiKit_8. I know that people are saying the ESP8266 is 5v tolerant even though it is a 3v3 part, but I would rather not risk it. So I needed to build a little voltage conversion circuit using a PN2N2222 transistor and three resistors (one is just to pull up my sensor device output to 5v). I wanted to house this in something to protect the GPIO HV<->LV circuitry and I decided a great way to make this work was to build a little box that the ESP8266 PCB could fit into that accommodated the USB input (for power/programming/datalogger) and had a Keystone jack on the other end to connect to my sensor. The sensor I am connecting is a Digiten G1 water flow sensor with 5v hall effect sensor.
I heated the little bridge lock piece with a lighter once I got 99% locked to make it pliable and easier to snap it all the way to 100%. Might redesign that area a little if I end up making some more projects with these Heltec parts. Perhaps shave 1mm off the bottom of the bridge.
I wrote some Arduino code that measures the flow rate and moves a little ball across the screen proportional to the flow rate. Indicator ball turns into multiple balls and moves faster as the water flow rate increases. This flow rate is fed via Wifi and MQTT into my OpenHAB2 controller where the data is logged into InfluxDB and graphed via Grafana. I just strap this little module right onto the CPVC pipe next to the Digiten G1 sensor, plug in the RJ14 jack and apply power via a USB cable. I can visually see when water is flowing and see the flow rate. Part of why I am using this is to detect slow leaks in my house and also foundation/slab leaks.
Supports are required.
Didn't take long to cleanup the Keystone jack area. Tolerances were near perfect, your printer calibration may be a little different than mine so you might have to adjust. I use a dial micrometer and I dialed an actual keystone jack which fit perfectly and snugly into the part. There is no provision to release the keystone jack locking tab once installed. If you need to release it, you might need to create an opening to depress the tab.
I used Blender, a dial micrometer, a keystone jack (RJ14 6 pin), and a single print. Print time was 2hrs on my G2S delta.