General References

(O) - Engineering Toolbox - This site hosts a very wide variety of reference tables and calculators. Topics range from physics, thermodynamics, and general math, to mechanical engineering, material science, hydraulics, HVAC, and more

More coming Soon…

General

(O) All About Circuits - This website hosts a wide variety of electronics learning materials including guides and lessons for beginners, calculators and references, technical articles, and industry news.

(O,B) Falstad Circuit Simulator - An online circuit simulator featuring animated current flow and scope / graph probing for circuit analysis.

(D) KiCAD - A free and open source electronics schematic and PCB design (EDA) software suite .

Retailers & Parts

(O) Adafruit - An online retailer and learning resource that sells electronics supplies and hosts a large library of learning resources and documentation often featuring their products.

(O) Digikey - An online electronics parts supplier offering a vast catalog of components, datasheets, and more.

Microcontrollers & Programming

(O) Arduino Reference - A simple command and library reference for programming Arduino (and Arduino-compatible) boards.

(O) Teensyduino - A series of powerful Arm-based Arduino-compatible microcontroller dev boards. The site also has extensive reference material for Teensy functionality and libraries.

(D) PlatformIO - An extensive development suite that turns Microsoft VSCode into an IDE for cross-architecture, cross-platform embedded software development. Includes library, board, and package managers, firmware compilers, serial communication tools, live debugging, and more, so you can write code, build it, and monitor your MCUs in a streamlined workflow.

ICs & Discrete Components

(O) SMD Marking Codes Database - An extensive database that allows users to identify small surface mount components from their marking codes.

(O) Adafruit Neopixel Überguide - A full guide covering installation, powering, and using the Adafruit software library for controlling Neopixels (WS2812B, SK6812, and similar addressable RGB LEDs)

Radio & Wireless

(O) RTL-SDR Blog - This blog hosts a plethora of guides, reviews, and resources relating to software defined radios and their applications.

More coming soon…

General

(O,R,B,D,M) 3D Printing Discord - One of the best online 3D printing communities, welcoming of all enthusiasts and anyone interested in learning / joining the hobby. The server features a diverse variety of channels including several help channels dedicated to community-led printer support. If you need help with your printer, or are shopping for a new printer, this is the place to ask.

Lectures & Youtube

(O) 3D Printing Basics Playlist - This series of videos, made by Thomas Sanlanderer, are a short but high quality introduction to the consumer 3D printing hobby. While this playlist is great, I must note some of Sanlanderer’s other content is of questionable ethics; his informational videos are fine, but do not trust his product reviews by themselves (seek additional reviews before buying anything he recommends).

3D Parts

(O,B) Printables - An online repository of 3D models and projects for printing. Previously known as PrusaPrinters and oriented toward Prusa owners, they have since re-branded and opened up to the wider 3D printing community. Many (including myself) agree that Printables is a true successor to Thingiverse. Printables even features a Thingiverse import tool for porting your models to their platform.

(O,B,M) MyMiniFactory - Another online model database. This one features a wide variety of free models, and an extensive marketplace for creators to sell paid models (figurines, minis, and tabletop gaming sets are very popular on MyMiniFactory). Every part uploaded to the site undergoes a review process where creators must prove their part is printable; no parts that cannot be printed are published.

(O,B) Yeggi - This is the Google search of 3D printing models. It searches a few dozen model repositories and collects the results in one place.

(O,R,B) GrabCAD - This is a resource for ready-made CAD files. These parts aren’t necessarily 3D printable, but are meant for use in 3D design and can be incorporated into assemblies as reference parts. Account registration (free) is required to access downloads.

(O,B,M) McMaster-Carr - This is an online hardware store. They offer full (free) 3D models of many of the items in their catalog, making them a great impromptu resource for parts to use in your CAD assemblies (such as gears, screws, etc.).

Software

(D) Ultimaker Cura - One of if not the most commonly used consumer 3D printer slicing (Gcode generation) applications. It’s free and open source and supports virtually any consumer 3D printer on the market.

(D) PrusaSlicer - Another extremely popular 3D printer slicing software. Though primarily marketed for Prusa 3D printers, it supports a wide variety of consumer 3D printers, and is also open source. SuperSlicer is a notable and more advanced fork of PrusaSlicer. Both are based on Slic3r.

Printer Technicals & Firmware

(O,B) Teaching Tech 3D Printer Calibration - A detailed guide (including videos) for first-time setup and full calibration of consumer 3D printers. If you’ve just gotten a 3D printer, I highly recommend spending a couple evenings stepping through this guide to get your printer running at peak performance.

(O) Marlin Gcode Reference - A command reference for Gcodes used by Marlin 3D printer firmware. Other firmware documentation is also available on the same site.

(O) Duet3D / RepRapFirmware Gcode Reference - A command reference for Gcodes used by 3D printers running RepRapFirmware. Other firmware documentation is also available on the same site.

A note about Thingiverse: It’s one of the oldest 3D printing model repositories and has a very large library of parts, but unfortunately, it’s been left to disrepair by its owners (MakerBot, who are owned by Stratasys). Download links regularly 404, the majority of models on the site are of poor (and unprintable) quality with inadequate means for community review, the search tool renders mostly irrelevant results, the site hosts malicious advertisers, and pages are slow to load. Though it’s a slow process, more experienced members of 3D printing community have been urging hobbyists to stop using Thingiverse and instead migrate to newer and more open platforms.
As such, I do not recommend using Thingiverse. instead, if you publish your projects online, please consider putting them on better platforms like Printables and MyMiniFactory.

(O) W3Schools - Hosts learning resources and references for several programming languages including HTML, CSS, JavaScript, XML, C/C#/C++

(O,B) RegExr - A playground for learning, building, and testing regular expressions (regex).

(O) Identifont - An online tool that can identify almost any font (seriously, their database is massive) by simply answering questions about its appearance. Site also has tools for choosing the right font for your application.

More coming soon…

(O,R,B) ChatGPT - If you’ve been following AI news recently, you’ve no doubt heard of this AI chatbot. You can ask it to do (literally) anything, so long as the answer is text-based, and it will do it. Given the right prompt, it can write essays, song lyrics, solve word problems, write entire programs in any programming language, and much much more. For your own sake, don’t use it to cheat, and don’t rely on it to be 100% accurate. Rather than spitting out an error if it doesn’t know what to do, it’ll usually give you a response that is (though confident sounding) very wrong based on whatever it thinks you want to hear according to the data it’s trained on. For the time being, ChatGPT is free for anyone to use after creating an account during OpenAI’s research period, however it will almost certainly become a subscription-based service after they’ve developed it into a finished product.