3-D printing system include development stations positioned to electrostatically transfer build and support materials to an intermediate transfer surface, a transfer station adjacent the intermediate transfer surface, guides adjacent the transfer station, and platens moving on the guides. The guides are shaped to direct the platens to repeatedly pass the transfer station and come in contact with the intermediate transfer surface at the transfer station. The intermediate transfer surface transfers a layer of the build and support materials to the platens each time the platens contact the intermediate transfer surface at the transfer station to successively form layers of the build and support materials on the platens. The platens and the intermediate transfer surface include alignment features. The alignment features temporarily join at the transfer station, as the platens pass the transfer station, to align the platens with the intermediate transfer surface as the platens contact the intermediate transfer surface.