You'll need adhesives to assemble certain printables, like attaching cupcake toppers to paper straws. A printable designer's go-to adhesive is usually a hot glue gun. They're inexpensive, and the glue is guaranteed to keep everything in place. You can also use glue dots, double sided tape (permanent is preferred), glue sticks, or regular tape.
The great thing about printables for personal use is that you don't need to have a fancy printer or pay a printing company a fortune. Simply print graphics at home with an inkjet or color laser printer. You can find a printer for as little as $60 or upwards of $2000. Don't think you need an expensive printer to create incredible graphics. A printer in the $100 range should work fine.