Useful sites for terrain printing


I’ve come across a few websites that make it easy to generate 3D models from terrain. The best part is that you can get relatively high quality models from these sites for free.

CADMapper is fantastic for creating detailed models, down to the level of individual buildings, and is free for areas up to 1 square kilometer. The site also has whole-city models for over 200 cities worldwide. Want to print Paris? Buy a spool of filament and go for it!

For terrain models of much larger areas, I’ve tried all kinds of methods, including downloading GIS data from USGS and using software utilities to create .stl models. But none of these work as well for me as Terrain2STL. The model of San Diego county in Southern California was generated from this site.

A final site I’m aware of is Terrain Party. It’s less intuitive to use than the other sites, but is also free and can produce good results.

If anyone’s familiar with other utility sites for 3D printing, please let me know via comments.

DIY Air Quality Monitor


If you’re at all concerned about the quality of air you’re breathing, you might be interested in an air quality sensor. For example, the Awair 2nd Edition is available on Amazon for $173, has great reviews, and not only detects particulates, but also chemicals, carbon dioxide, and measures humidity and temperature. It also has Alexa integration and a companion mobile app.


For a lot less than this, if you’re willing to forgo some of the features, you can make your own sensor, like the one pictured above, for around $36. I’ve sourced the key components from Amazon, but that’s only because I’m lazy (and please note: these are not affiliate links; I’m not getting compensated for any of this). If you source from eBay or larger components retailers like Mouser, you might be able to bring the cost down a bit.

Here’s your shopping list:

  1. mini OLED display from Amazon for $7
  2. Arduino Uno from Amazon for $8.49
  3. Dust sensor module from Amazon for $19
  4. 9V battery connector from Amazon for $6 (pack of 5)

So what does this version do? Basically it uses Sharp’s GP2Y1010AU0F particulate sensor to measure dust and other stuff in the air, measured in micro-grams per cubic meter of air volume. You might be a bit skeptical about this (my picture shows nothing detected) but place this device on a carpet surface and stomp around it, and you’ll be surprised (or maybe grossed-out) by what the sensor measures. If you want to geek out the spec sheet for the module has all kinds of detail about how it works, including a reference guide for what constitutes “excellent” (0-35 μg/m^3) and “average” (35-75 μg/m^3) air quality.

OK, so how do you build one?  Easy:

1. Source the parts above. I didn’t mention wires for connecting the components, but these are super cheap and you don’t have to use prototyping connectors; you can also solder the connections if you want.

2. Wire everything up.  The OLED display connections are: SDA->A4, SCL->A5, GND->GND, VCC->5V.  The sensor module comes with a connector with 4 leads: yellow wire-> D7, blue wire->A0, black wire->GND, red wire->5V.

3. Load the sketch onto the Arduino Uno. I’ve saved the sketch file (.ino) and the two .stl files here.

4. 3D print the base and display holder. I tried to make this a single object file, but both pieces print better for me (Ender 3) as separate pieces. I super-glued the display bracket to the main base.


That’s it! Breathe easy.