Substiports: User-Inserted Ad Hoc Objects as Reusable Structural Support for Unmodified FDM 3D Printers

We contribute a technical solution to reduce print time and material with unmodified fused deposition modelling printers. The approach uses ad hoc objects inserted by a user during printing as a replacement for printed support of overhanging structures. Examples of objects include household items like books, toy bricks, and custom mechanisms like a screw jack. A software-only system is integrated into existing slicing software to analyze generated support print paths, search a library of objects to find suitable replacements, optimize combinations of replacement objects, and make necessary adjustments to impacted printing layers and paths. During printing, the user is prompted to insert objects with the help of lightweight printed holders to guide placement and prevent movement. Instructions printed on the build-plate help identify and position objects. A technical evaluation measures performance and benefits with different sets of ad hoc objects and different levels of user involvement.