Multi-material stereolithographic three dimensional printing

A method of multi-material stereolithographic three dimensional printing comprising:

• (a) providing a stereolithographic three dimensional printer comprising a platform, wherein a portion of the platform comprises an optical exposure window;
• (b) depositing a first material through a first material dispenser of the stereolithographic three dimensional printer onto only the portion comprising the optical exposure window to form a first material layer;
• (c) curing at least a portion of the first material layer to form a first material structure on a build head of the stereolithographic three dimensional printer;
• (d) using at least one cleaning device to clean (i) a surface of the optical exposure window, (ii) a surface of the build head, or (iii) a surface of the first material structure;
• (e) subsequent to (c), depositing a second material through the first material dispenser or a second material dispenser onto only the portion comprising the optical exposure window to form a second material layer;
• and
• (f) curing at least a portion of the second material layer to form a second material structure adjacent to and over the first material structure,
• wherein, in (c), the optical exposure window is substantially free of a material different than the first material, and
• wherein, in (f), the optical exposure window is substantially free of a material different than the second material.

A method of multi-material stereolithographic three dimensional printing comprising:

• (a) depositing a first material through a first material dispenser of a stereolithographic three dimensional printer onto an optical exposure window to form a first material layer;
• (b) curing at least a portion of the first material layer to form a first material structure on a build head of the stereolithographic three dimensional printer;
• (c) using at least one cleaning device to clean (i) a surface of the optical exposure window, (ii) a surface of the build head, or (iii) a surface of the first material structure;
• (d) subsequent to (c), depositing a second material through the first material dispenser or a second material dispenser onto the optical exposure window to form a second material layer;
• and
• (e) curing at least a portion of the second material layer to form a second material structure adjacent to and over the first material structure,
• wherein (c) and (d) are performed simultaneously,
• wherein, in (b), the optical exposure window is substantially free of a material different than the first material, and
• wherein, in (e), the optical exposure window is substantially free of a material different than the second material.