Multi material 3D printers have been available for a few years now in the Stratasys Eden and Connex range of printers, by mixing base resins within the printer and jetting them onto a build platform in a similar way to an inkjet 2d printer they are able to produce digital materials with varying translucency, rigidity, thermal resistance or color. The main benefits for this are to simulate over moulding, produce multi material single print parts or a variety of parts with different specifications in the same build, it can also reduce the need for post processing like painting.
With an array of new light curing resins becoming available for SLA and DLP printers it is possible to print an object as soft as silicone right through to rock hard. The problem with using multiple materials in SLA and DLP is they use a VAT filled with anything from a few 100 ml’s to several litres of a single resin, pouring two resins in a single Vat will do you no good for multi material printing.
Reinout Holtrup, a student of industrial design at the University of Twente in the Netherlands set out to solve this issue by creating the XZEED. For his bachelor assignment he created a prototype for a DLP 3D printer which can print with up to 5 materials/colors at once. Utilizing several Vats instead of just one he lined them in a row with a mechanism to shift them on a horizontal axis, aligning a single Vat with the projector cures the selected part/layer with the corresponding resin, to shift Vats is to change resins. A very clever and simplified solution to that of the Stratasys machines and one I am sure that will gain a lot of attention.