For commercial printing you can use these files.
Many home printers are capable of handling slightly heavier paper suitable for postcards. US postal mail requires a minimum weight of at least 55lb (145gsm) cardstock for postcards. These files will print 2 postcards per page (2-up). To make double-sided cards including the lines for the back of the card, your printer may require running the page through the printer twice (some experimentation is needed). Trim marks have been provided so that you can see where to cut.
Protest signs can be printed up to A3 size and used during the march.