Presence of complex bone defects in osteomyelitis treatment may be challenging for the surgeon. Antibiotic cement spacers take a role in managing these defects. The available techniques and systems of antibiotic cement spacers have their pros and cons. There are cases in which these standard options may fail, mainly due to stability related issues. In this report, we present an antibiotic spacer technique in a very complex bone defect that is prone to failure if managed by routine spacer applications. Anticipating that any standard spacer application methodology will fail, we decided to make our own custom antibiotic cement spacer. We used the patient's uninjured side's tomography data to create a custom 3D spacer mold model with the help of a computer software. Later this 3D spacer mold model was printed with a 3D printer. The print out was sterilized and used to cast a custom antibiotic cement spacer resulting in a perfect fit in the defect.