Open source software licenses can be also used for non-software works and are often the best choice, especially when the works in question can be edited and versioned as source. Choose an open source license.
CC0-1.0, CC-BY-4.0, and CC-BY-SA-4.0 are open licenses used for non-software material ranging from datasets to videos. Note that Creative Commons does not recommend its licenses be used for software or hardware.
Any open source software license or open license for media (see above) also applies to software documentation. If you use different licenses for your software and its documentation, be sure to specify that source code examples in the documentation are also licensed under the software license.
The SIL Open Font License 1.1 keeps fonts open, allowing them to be freely used in other works.
Designs for open source hardware ranging from furniture to FPGAs are covered by CERN Open Hardware licenses: CERN-OHL-P-2.0 (permissive), CERN-OHL-W-2.0 (weakly reciprocal), and CERN-OHL-S-2.0 (strongly reciprocal).
If your project contains a mix of different types of material, you can include multiple licenses, as long as you are explicit about which license applies to each part of the project. See the license notice for this site as an example.