3. Portable charger

Build a portable phone charger out of an Altoids box. I’d recommend eating the mints first, though. Find out what you need and how to build it here, or grab a kid from Adafruit!

4. Slime

Everyone loves some good homemade slime. Our sister site, CNET, has a whole recipe guide of borax-free slime that you can make with (or without) the kids! Some people have encountered some problems with borax-based slime in the past, so CNET found three recipes that ensure safe fun.

5. Raspberry Pi

Create your own mini PC with this Raspberry Pi starter kit. You can plug it into a TV or other display and run an internet browser or your office suite of choice. Here’s a quality, expansive starter kit.

6. AI assistant

Build your own voice-controlled AI assistant using Raspberry Pi. While this option is on the more expensive end–just over $100–you can still create an AI assistant for much cheaper than a store-bought one. Whether via kit or individually purchased parts, a Raspberry Pi-powered assistant is a fun prospect.

8. Soda can robot

With no Arduino or Raspberry Pi necessary for this little guy, the soda can robot is an easy and fun DIY project. Grab a DC motor and some household items, and soda can robot is alive and walking. Here’s how to make it and here is a kit to make it even easier.

9. Crystals

Grow your own crystals! With only three ingredients–epsom salt, food coloring, and a bowl–you can grow crystals in your own kitchen! Or you can go here to make more advanced crystals.

10. Lightsaber

Channel your inner Yoda with your own personal lightsaber! With a more complicated assembly, the lightsaber is powered by the Arduino MKR Zero. Here are written instructions, along with a video, to get your lightsaber up and running.

11. Propeller car

Propeller powered cars are fun for engineers of all ages. Race your cars against each other and try building with different materials! Here is a wood-based, easy design.

12. Bottle Rockets

Bottle Rockets are a classic. Not the most sophisticated of projects, but extremely fun to watch. Here‘s how to make your bottle rocket take flight.

13. Fossils

Go for a fossil hunt! Regardless of the likelihood you find a fossil, going for a hike outdoors and studying ecology along the way never hurts. Here are some of the best fossil hunting spots!

14. Volcano

Make a volcano out of lemons! This project will definitely need to be taken outside, but all of the fun colors make it a sight to see!

15. Pocket game console

Take games like Tetris and Snake anywhere. Using Adafruit Pro Trinket, you can put together your own pocket-sized gaming system! Here’s what you need and how to assemble it.

16. Radio

Use a circuit to build your own FM receiver. You can also build radios with an AM connection. Here are plenty of videos and step-by-step photos to get you started.

17. Herb box

Grow your own fresh herbs in your kitchen. DIY Network‘s herb box uses a weather-resistant wood, if you want to keep it outside. You can also place your herb box right on your kitchen countertop or window sill.

18. Dog food dispenser

Are you going to be out of the house for the day? If so, an automatic dog food dispenser may come in handy. Made out of cardboard, you can build this gadget right in your own home.

19. Automatic watering system

Use an Arduino Uno and Genuino Uno to automatically water your plants! If you’re going on vacation during the summer, this DIY gadget can help keep your plants alive and well. Here are instructions on how to get started.

20. Egg drop challenge

tThe egg drop challenge is always a fan favorite. The goal is to use various material to protect an egg from breaking when dropped from a significant height. This game requires brain power and creativity, which are good to exercise at any age.

tWhat are your favorites? Tell us in the comments or on Twitter.

Also see

• The best alternatives to the Raspberry Pi (free PDF) (TechRepublic)
• What are the best Raspberry Pi alternatives? Everything you need to know about Pi rivals (ZDNet)
• Raspberry Pi: A cheat sheet (TechRepublic)
• Build a cheap computer for your kids with Kano OS and a Raspberry Pi (CNET)
• Hone your Arduino skills with this e-book bundle (TechRepublic)