Depending on the project, you may be cutting PVC with a cutting tool or saw, gluing pipe, cleaning with strong solvents, working with power tools (for wood pieces) or other potentially dangerous activities. Read and understand the instructions of any tools you use. Generally speaking, the faster and easier a tool makes a job the faster and easier it can bite if you’re not careful.
We highly recommend using and wearing protective gloves; I use nitrile gloves. Many chemicals used to clean and glue PVC pass straight through your skin, which means your liver is the next stop–do that often enough and your liver will make you very unhappy. (The secret to working with gloves is to get a material like nitrile or latex which is “stretchy” and form-fitting, and to not get too big a size.) If you use plastic gloves keep in mind that PVC glue may also be glove glue; my nitrile gloves don’t seem to be strongly attracted to the glue, but it’s possible you may end up with additional decorations on your project if you’re not careful.
The chemicals also emit potentially dangerous fumes. Work in a well ventilated area, preferably outside of your home. Take precautions not to breathe in any dust created when sawing wood or PVC.
When cutting pipe there is the possibility of it shattering (though it’s very rare); wear safety glasses while using a cutting tool of any sort.