Apparently, PTFE white matte thread seal tape wrapped around a white polymer eraser works well as a white balance reference. Photography Life has an article with examples of its use:

• DIY: Reliable and Cheap Universal White Balance Reference Device.

While better than nothing, it does not address color correction at all. The colors you end up with are whatever the profile you're using produces. The profiles used by some software for some cameras are clearly inaccurate.

Some people have made DIY clones of color charts using color swatches. (I reference these particular examples because they specify the exact swatches used to create the charts.)

• Gretag MacBeth clone using Pantone swatches.
  Instructables: DIY Color Checker

• SpyderCheckr clone using Behr paint swatches ("Poverty Checker")
  YouTube: How to make a FREE COLOR CORRECTION chart

While this approach is superior to using white balance alone, absolute color accuracy is not ensured because few, if any, of the swatches are exact matches for the original charts. For instance, when using the Poverty Checker against SpyderCheckr reference data, the result is more saturated than expected. This occurs because the patches of the SpyderCheckr are highly saturated and the grayscale patches have a blue/cyan tint.

DIY charts used with commercial reference data can still be used to ensure relative color consistency across multiple cameras and lighting conditions.

To improve the accuracy of DIY charts, open-source software (Argyll, DCamProf) can be used with swatch-specific color data to generate camera profiles. Target colors and ΔE color difference can be searched at Encycolorpedia.

Even better would be to measure the color of the swatches with a tristimulus colorimeter, color analyzer, color difference meter, spectrophotometer, etc. These devices usually cost a few times more than the charts in question, but may be considered to have paid for themselves if they are used to create multiple charts. They can also be used to profile printers and scanners.