Background The current simulators for teaching oncoplastic surgery marking are available in a fixed size for each model. This is not an accurate reflection of the variety of patient’s breast volumes in reality and may limit the teaching to certain techniques associated with the particular breast ptosis/size. Device description This is the first reported simulator with varying breast volumes/ptosis in a single model for teaching oncoplastic surgery marking, known as Adjustable Breast Oncoplastic Surgery Simulator (ABOSS). Adjustable Breast Oncoplastic Surgery Simulator was created using 3D printing. Preliminary results Adjustable Breast Oncoplastic Surgery Simulator could simulate the breast in appearance and texture. It is inexpensive and allows the practice of various markings based on the different breast volumes/ptosis in a single model. It also allows for the practice of the marking needed in asymmetric breasts to correct the asymmetry. Current status Plans for commercialisation were made.