The Beinecke Rare Book & Manuscript Library at Yale University has several hundred images online from the Filippo Tommaso Marinetti Papers. Marinetti was one of the leaders of Futurism. The collection includes many historical photographs (notes on back scanned as well), some writings, and printed materials. It is possible to download at least two different sizes of each image by clicking through to the image size needed and then right clicking (control-click on a Mac) to save the image locally. The largest images are actually a bit bigger than what is needed for PowerPoint; the medium images will work for PowerPoint as long as they are not stretched to the point of pixelating.