WAGO Lever Nuts

I use these things A LOT! They are great for temporary builds, as you can very easily disconnect and reconnect wires using them. They are also certified for permanent installation. Best of all- they will connect everything from 20AWG "alarm" or "network" cable up to 10AWG, mix and match, stranded and solid! They are good..

USB/Power Adapter Hack

The little D1 Mini controllers I use, and other gadgets like Raspberry Pis, run on USB-style adapters. You can get various sizes and shapes of these "wall worts" dirt-cheap, and probably have a bunch in a junk drawer somewhere. So- what do you do when you want to use them in, say, a waterproof junction..

Fuse Holders

You are dealing with DC electricity operating at a fairly high current. You don't want your roof, yard, shed, outhouse, etc. to catch fire. You want to protect your wiring with fuses! Some will advocate those fancy in-line automotive fuse holders. Others are big fans of marine fuse blocks, or even more expensive- "Distribution" boards...