Corn Starch Paint

Description Temporary paint made with corn starch, water, and pigment (either food coloring or tempera paint)
Typical Dimensions 16oz box standard in most supermarkets. Bucket size available at wholesale stores.
Estimated Cost $18 / 24-pack of 16oz boxes.
Durability Demo: 1 day to 1 month installation 

Bikeways Use corn starch paint in conjunctions with stencil to create pavement markings, or other colored treatments (lanes, bike boxes, two-stage turn queues etc.)
Pedestrian Crossings Use corn starch paint to create artistic / decorative crosswalks.
Curb Extensions and Plazas Painted surfaces will enliven the new public space and clearly delineate pedestrian space from vehicle space.
Roundabouts / Activated Alleys Colorful mural surface treatments add beauty, space definition, and can help calm traffic.

Sweep or pressure wash street to remove roadway debris before applying.
Easy to make and wash away, and it's non-toxic. 
Mixe equal parts corn starch and water, and add pigment using either tempera paint or food coloring.
Highly sensitive to weather conditions and will only be good until the next rain storm. Thus, it's only appropriate for very short-term demonstration projects.

Local supermarket or wholesale stores such as Costco.