1. A computer-aided design (CAD) computer system comprising: a computing device; a network interface; a non-transitory data media configured to store instructions that when executed by the computing device, cause the computing device to perform operations comprising: provide for display on a first user terminal an interface enabling a first user to select one or more design elements; provide for display on the first user terminal an interface enabling the first user to specify a plurality of types of proscribed content; receive, via the network interface, from the first user terminal, a user design element selection including at least a selection of a first design element; receive, via the network interface, from the first user terminal, a specification of proscribed content; store the specification of proscribed content in association with at least the first design element; enable a second user to access, via a second user terminal, the first design element; access the specification of proscribed content associated with the first design element; provide, for display on the second user terminal, a design customization user interface enabling the second user to combine digital content with the first design element, wherein the digital content comprises image, text, and/or audio content; determine, using an analysis engine, whether content combined by the second user with the first design element includes content included in the specification of proscribed content, wherein the analysis engine is configured to perform image, textual, and/or audio analysis; at least partly in response to a determination that the content combined by the second user with the first design element includes content included in the specification of proscribed content, inhibit printing on a physical item and/or electronic distribution by the second user of the first design element with the content combined by the second user; and at least partly in response to a determination that the content combined by the second user with the first design element is not included in the specification of proscribed content, enable printing on a physical item and/or electronic distribution by the second user of the first design element with the content combined by the second user using one or more sharing platform.