Glioblastoma multiforme (GBM) is the most common and malignant primary brain tumor in adults. The existing treatment for GBM, which involves a combination of resection, chemotherapy and radiotherapy, has a very limited success rate with a median survival rate of less than 1 year, mainly because of the failure of early detection and effective treatment. We present a novel 3D GBM cell culture model based on microwells that could mimic the in vivo environment and help to bypass the lack of suitable animal models for preclinical toxicity tests. Microwells were fabricated from simple and inexpensive PEG material for the control of in vitro 3D culture. The viability of the spheroids generated in this manner was quantitatively evaluated using live/dead assay and shown to improve over 21 days. The proposed novel platform could be useful and cost-effective for high-throughput screening of cancer drugs and assessment of treatment responses.