Isn't the Marxist conception of this based on exchange of labor time? In other words, if you were willing to exchange what you made during your time painting with whatever someone else was doing during their time working, then this is the basis of the economy now, and can be a basis of a future economy. An example would be a farmer grows food and exchanges those commodities with someone who makes clothes. Both share the commodities made during their labor time with each other, it's basically an exchange of labor time.
-- Lance