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Recently, 3D printing technology has become a practical method to realize products rapidly. It is suitable for making small quantities of products. Although it is capable of printing with a high level of geometric complexity, there is a lack of tensile strength due to its process where the products are printed layer by layer. However, this technology is potentially to be combined in a composite manufacturing process. Mostly, a composite product is made by using a mold. This mold is relatively expensive and can only create a product with less complexity. Nevertheless, the composite product has main advantages such as light, strong, and flexible. Therefore, combining these two technologies is a new breakthrough in realizing products with high complexity, light, strong, and flexible. This study aims to determine the mechanical properties of sandwich composite filled with 3D printed product as a core. Several parameters were varied including core thickness and skin thickness. The skin material was a Glass Fiber Reinforced Polymer (GFRP) while the core material was 3D printed Polylactic Acid (PLA). The tensile and bending tests have been done in accordance with ASTM D638 and ASTM D790. The results showed that the addition of GFRP skin on the sandwich composite could significantly increase the tensile strength but did not have an impact on the flexural strength. The highest flexural strength of 50.36 MPa was achieved at 3 layers of GFRP skin while a remarkable tensile strength of 55.74 MPa was obtained at 4 layers GFRP skin. Moreover, the addition of core thickness also does not have an impact on flexural strength. The flexural strength of the 3D printed core was around 20 MPa for all thickness. However, when 2 layers of GFRP skin were used, a remarkable flexural strength of 57.67 MPa was obtained but the flexural strength was then decreased when using 10 and 15 mm cores.

In Faculty of Industrial Technology Islamic University of Indonesia, whiteboards are used as a medium of learning in the classroom. Generally, instructors use non-permanent markers to make it easy to clean with an eraser. The problem that occurs is if this eraser is often used, the ability will decrease. This is caused by the large amount of ink markers that have been attached to the eraser cloth so that some ink that can not stick in the form of fine grains eventually falls and collects in the dirt container. These fine grains can contaminate clothes, hands, and other body parts. In addition, there are remnants of ink markers on the board that can hinder to write the next material. But to overcome this, there is a contradiction that is if an eraser is often used, the ability will decrease. To eliminate this contradiction, a systematic method of problem solving was used, namely TRIZ method. This method helps to provide solutions through the principle of preliminary action. This principle was realized by adding a spray mechanism that is used just before the erasing process is carried out. Testing the ability of the eraser was done on a whiteboard with ink markers with the size of 50 x 50 cm. The results show that the new eraser that has been developed is able to bind more ink markers and can completely erase so that it can write the next material clearly.