Whole breast irradiation is the standard treatment for patients with early-stage breast cancer. We previously developed a personalized breast support device (PERSBRA) that reduced heart and lung radiation exposure. However, the skin dose was concerned for the device due to its thickness. In this study, we designed the new honeycomb structures to reduce the dose to the skin and maintain stable breast position with this device. Three different structures of PERSBRA were designed. They were solid structure, honeycomb structures with 3.5 mm wall thickness and honeycomb structures with 4.5 mm wall thickness respectively. Those patients who scheduled to receive whole breast irradiation were enrolled for anthropometric breast position analysis. Stability of breast position in supine with PERSBRA were analyzed by scanning with a 3D infrared scanner. The distances between the nipples, between the nipple and the xiphoid process, and between the nipple and the inframammary fold were used to be the index. 32 patients were enrolled for anthropometric breast position analysis. The skin dose was simulated using the thermoluminescent dosimeter (TLD) positioned on the phantom with PERSBRA in the treatment scenario. The displacements between two nipples, the nipple and the infra mammary point, and the nipple and the xiphoid process were 1.4%, 1.2%, and 0.4% for 3.5 mm honeycomb structure. Meanwhile, these displacements were 0.8%, 0.7% and 0.2% for solid 10% structure. Compared to these results, there were no significant difference for the two designations. The surface dose simulating the treatment scenario were 78.27%, 89.39% and 91.9% of prescribed dose for the 3.5mm, 4.5 mm honeycomb structure and the solid 10% filled structure, respectively. The 3.5 mm honeycomb structure reduce the surface dose significantly compared to another two designations. The honeycomb structures do not jeopardize mechanical properties of PERSBRA or the breast positional stability support. Moreover, honeycomb structure with 3.5 mm thickness effectively reduces skin surface dose on a breast phantom. These data encourage further clinical studies to investigate the effects of such design on radiation dermatitis during whole breast irradiation.