**8. 3D Bioprinting**

3D printing, better known as bioprinting, has been widely accepted in the health industry. This was initially developed to print 3D process designs in the gastronomy industry. Later on, it has become one alternative medicine for organ replacement. Printing with organs like heart, liver, kidney, replacement hip bones, and maxillofacial trachea has become an alternative in association with research on stem cells to regenerate tissue. Eye level attempts have been cast for 3D modeling and future impressions of the eyeball for cosmetic purposes in people requiring ocular prostheses turned what was previously artisanal towards a more precise subsequent enucleation process. This improves the aesthetic value and lowers the probability of infection that occurs in these tissues due to poor hygiene because there is no need to frequently remove it for cleaning purposes [15].

This process consists of the printing, layer by layer, on a 3D printer using stable biological materials applied in tissue engineering. Very few materials, which fulfill the requirements for bioprinting as well as provide adequate properties for cell encapsulation during and after the printing process, are available. Some of the materials that are similar to the contact lens hydrogel composite or include alginate and gelatin precursors were tuned with different concentrations of hydroxyapatite (HA) and were characterized in terms of rheology, which is the swelling behavior and mechanical properties used to assess the versatility of the system properties [16].
