This chunk of fordite looks like a slice of cake

Pretty much. For sure specifically is oversparyed paint removed from the old spray booths where ford cars were painted in a specific year range. The excess paint would coat surfaces around the booth and dry there. Over many thousands of cars and color changes the paint would form layers over older paint and build up. When removed these cups and chunks not only look neat, but carry some historical significance since there is a cultural and historical weight behind Ford and it’s plants. Polished to a shine and even shaped, people make jewelry and ornaments from it. It’s important to note however that dried paint in general is toxic, but the paints used at that time were even more toxic than modern paint. Much Fordite contains lead and other hazardous materials. Wearing it, especially if it is “sealed” should pose minimal threat, but working with it, or being exposed to any dust etc from compromises Fordite can pose health risks.