Yes, but I don't want it to stand out when mounted on the wall. I have luminous yellow PLA and heat shrink too, but that also didn't seem like a good idea 
Ah, just realised your comment was probably tongue in cheek.
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I am using shelly HT sensors and nodeon enocean HT sensors.
The enocean sensors are a bit pricey but can run without a battery as they use solar power.
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another very easy way to connect one wire DS18b20 to node-red is the use of shelly 1 pm with a shelly extension for connecting one wire DS18B20. You can use http request or mqtt.
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Couldn't the sensor go on the inside of the case, away from the processor(heat), of course.
Thank heavens there are still people who build their own devices without Tasmota, Sonoff or Shelley's. I build all my own to do exactly what I want and to high standards of electrical safety.
I have run multiple 18b20's on a Wemos D1 mini single IO pin with no problem at all provided the connecting cables are of similar length. I always use the fully powered mode not parasitic, If one needs to have a sensor(s) with significant longer cable(s) then it is best to use a separate IO pin for the longer cable and a second instance of the Dallas library. For example I have four sensors with cables of 2m, 2m 3m and 4m on one pin, a fifth sensor with a 20 m cable worked better on a separate in. Sensor wiring was radial not daisy chained.
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Difficult to get decent separation when you are looking for good measurement. The sensor needs to be in free flowing air. In principle you could have it in a separate, well ventilated compartment, but I prefer just to make it project.
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I have several ESP8266 running Tasmota, LM2596 and the BME280/680 for sensing.
I had standard boxes and cut a slot in the lid just big enough to poke the sensor only out through the slot and made sure that the convection currents flow over the sensor (vertical orientation). Reading compares well with reference calibrated device.
Now have a 3D printer so interested in observations.
Yes, of course. But you do need access to air, especially if you want to do humidity sensing. In fact even vaguely accurate humidity sensing needs a guaranteed airflow (e.g. a fan). For home use, don't expect humidity accuracy within 10%. While the sensors claim higher accuracy, you will never get that in real life - at least without fan-driven air flow.
An option would be to use zigbee-sensors:
For example:
I'm using several Xiaomi sensors (temperaure, humidity, door/window) connected to a zigbee-adapter (coordinator) sending data to node-red via mqtt.
I'm also testing a Sonoff-ZBBbridge with Tasmota.
It's running for a couple of weeks now without any issues.
Thanks for the feedback which I think will be valuable to many reading this thread. As a professional heating engineer I am only too aware of the need for air flow over sensors. I spend lots of time trying to convince people to put their CO detectors, or smoke alarms, in a place were they have any chance of working properly. In this forum topic my question was about the DS18B20 sensor so humidity was not a factor. Just about every commercially available domestic room thermostat has its sensor inside a vented enclosure for aesthetic reasons, not that I am saying it is an optimal situation. Your comments regarding air flow for a humidity sensor are spot on and in fact I have done exactly what you describe by fitting a BME280 inside two 90° plastic elbows, to create an inverted U, with a 50 mm, 12v fan to provide air flow. It works well outside and is weather proof.
Thanks Bob. I'd love to see a write-up of that setup at some point. I need to do a new external sensor.
If you are looking for industrial version of the temperature sensor, then we might be able to help 
We provide low power wireless temperature sensors (BLE 5.0). in a harsh environment (IP67 waterproof). Temperature data is sent out every 10 seconds. Measurement accuracy is within +/-0.3 degree C in the range of -40 to 125 degree C. The battery lasts at least 3 years (average 4 years depending on the environment). The sensing element is at the bottom of the sensor so that you can glue it to the structure to monitor to get accurate reading.
Wireless sensor is plug & play to the gateway. The gateway supports hundreds of such sensors at the same time (Each sensor has unique ID). The gateway uses Node Red and then sends data out via MQTT to anywhere you want.
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OK, I'll see what I can do in the next few days .
You forgot to mention the all important price! and a web site.
I have ordered these Wemos D1 Mini.....but I also had seen some zigbee devices; do I need a hub or something to connect to my network? I thought it would be good to see what they are like.....and they are fairly cheap. Have you tried some? What is your setup?
Cheers,
Ant
What's the cost? Link?
Regards,
Anthony
Yes, you need either a hub or a Zigbee dongle that connects to your server. If you get a hub, make sure you can control it remotely though.
Sorry I don't know if it is appropriate to post the price info here. 
Here is the link to the wireless sensor:
Wireless Low Power Sensors (broadsens.com)
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Here is my setup:
- Approx. 40 zigbee devices (Xiaomi and Aqara)
- Zigbee-Adapter, Texas Instruments CC2531
- zigbee2mqtt, v1.17 on an old Raspberry pi 2
I would start reading the doc on zigbee2mqtt.io (see the link I already posted).
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