Color mixing nozzle

1. A printer head for an extrusion-based 3D printer, the printer head comprising n distribution elements, wherein n≥2, a combination chamber, and a printer nozzle, wherein the combination chamber is configured downstream of the distribution elements and upstream of the printer nozzle, wherein each distribution element comprises a flow-through chamber with an inlet for a 3D printable material and a plurality of k outlets to the combination chamber, wherein k≥4, each distribution element being arranged to distribute the 3D printable material by the plurality of k outlets, wherein the outlets of the distribution elements are configured such that a plurality of outlets of a distribution element have outlets of another distribution element as nearest neighbors.

2. The printer head according to claim 1 , wherein the outlets of the n distribution elements are distributed over an outlet area, wherein the outlet area is configured upstream of at least part of the combination chamber, and wherein at least 90% of the total number of outlets of a distribution element have outlets of another distribution element as nearest neighbors.

3. The printer head according to claim 1 , wherein the outlets of the n distribution elements are configured regularly distributed about the periphery of a surface defined by a circle, oval, or polygonal shaped outlet area.

4. The printer head according to claim 3 , further comprising a conically shaped element having a base configured between or upstream of the ellipse-shaped outlet area and an apex directed to the nozzle, and wherein one or more of the outlets and the printer nozzle have an equivalent circular diameter of at maximum 2 mm.

5. The printer head according to claim 1 , wherein the combination chamber has an average equivalent circular diameter that is larger than an equivalent circular diameter of the printer nozzle.

6. The printer head according to claim 1 , wherein, for a given n=number of distribution elements and k=number of outlets per each distribution element the printer nozzle has an equivalent circular diameter of at maximum 200 μm*n*k.

7. An extrusion-based 3D printer, comprising a printer head according to claim 1 , and a 3D printable material providing device configured to provide 3D printable material to the printer head.

8. The extrusion-based 3D printer according to claim 7 , wherein the 3D printable material providing device is configured to provide n 3D printable materials to the n distribution elements, respectively.

9. The extrusion-based 3D printer according to claim 7 , comprising two at least two printer heads, wherein the printer nozzle of a first printer head is configured upstream of the inlet of a distribution elements of a second printer head.

10. The printer head according to claim 1 , wherein each of the k outlets of the n distribution elements have equivalent circular diameters selected from the range of about 60-200 .mu.m.

11. A method for 3D printing a 3D item, the method comprising depositing m 3D printable materials to provide the 3D item comprising 3D printed material, wherein m≥2, the method comprising feeding the m 3D printable materials to at least m distribution elements of the printer head according to claim 1 , and depositing the 3D printed material.

12. The method according to claim 11 , wherein the m 3D printable materials comprise different thermoplastic materials.

13. The method according to claim 11 , and wherein the m 3D printable materials are 3D printable materials having different colors.

14. The method according to claim 11 , wherein the 3D printed material comprises plurality of domains originating from the m 3D printable materials, wherein the method comprises controlling the dimensions of the domains to have a largest width which is at maximum 120 μm.