Vectr is pretty simple and doesn’t have as steep of a learning curve as other, more intricate graphics programs. Vectr is a free graphics editor that you can download or use online.Adobe also usually offers free trial periods for their products.
Public libraries or schools will often have Adobe Creative Suite installed on public computers.But, if you can’t afford these programs, there are several alternatives! The base requirement is that the program you use has layers, as your line work and colors should be separated. (Vector graphics are the most crisp and clear, and they’re usually AI, PSD, or EPS/PDF files.) Adobe Photoshop and Illustrator are best-suited for this. You can start with a hand-drawn sketch, but manufacturers will need your design to be sent in a printable vector file.