An endangered species of indigenous fish is getting some help from a New Zealand Cardio-thoracic Surgeon, Mr. David Shaw. Some of the proceeds from selling his specially designed chocolate fish are going towards improvement of the waterways where the fish breed. To learn more and buy some click here. The 3D lab at the University of Canterbury was asked to 3d scan a full size carving of an adult fish and create a 3d printed version for making the chocolate fish moulds.
How?…The carving was of a full size adult giant kokopu. A chocolate bar that size would be very unhealthy! So we needed to create a virtual model of the carving and scale it down. Vacuum formed plastic sheet over a male “plug” would form the chocolate mould. Vacuum forming is the opposite of blow moulding used to plastic drink bottles. The process is often used for making the clear plastic packaging for toys or household goods. Click here to learn how to make your own 3D printed vacuum former.Thin sheet plastic is heated and then sucked down over a plug. For this application the production requirement meant making many moulds so the plug had to be reusable.
To create the virtual model for printing, the carving was scanned using an Artec Spider hand held 3D scanner. This device is excellent for capturing very fine detail, but can be a bit difficult to use. The associated Artec Studio software was used to create the virtual model and it was saved as a ###.stl file for 3D printing. Using Meshmixer, the virtual model was cleaned up and scaled to a size that would give the desired 400g chocolate bar.
A Stratasys Connex polyjet 3D printer was used to make the plug. This machine was used because the surface quality is very good and the material could handle the temperature of the vacuum forming. A desktop FDM printer ABS or PLA is also suitable but the surface finish and detail are not as good. Click here to learn how you can make your own vacuum former.