The phantom was designed using the Fusion 360 computer-aided design (CAD) software and then exported as an **.STL** file for 3D printing. The base design is an 18 cm modular cylinder split into two parts along its length with open ends. The bottom half has two longitudinal railings where the top fits, leaving two round holes centered in the middle for inserting antennas. The cylinder sides can then be closed with the lids. The top has two square openings for pouring of the conductive mixtures. A 0.1 mm gap was used for all fitting parts to account for the 3D printing resolution. The phantom's full dimensions are presented in Appendix B. For instructions on how to build the conductive mixture see the main text of our publication. The inside of these lids can then accommodate the outer ear canal and concha shape to create an imprint on the material inside, where an ear-EEG device can be placed for testing. The current methodology used ear canal scans by a professional audiologist, digitally scanned on-site, and delivered as an **.STL** file which can be imported as a mesh to Fusion 360 and easily fused with the lid mesh by using the *Mesh Menu -- Modify -- Combine-- Join* Operation The ear-EEG phantom prototype was 3D-printed on a Prusa i3 MK3 3D printer using polylactic acid (PLA). PLA was chosen due to its ease of use, fast printing times, affordability, non-warping nature, and lack of post-processing requirements. The printing settings on the Prusa software were set to a 0.15 mm *QUALITY* printing resolution, using Prusament PLA filament with a default structural infill of 15%. The software automatically added necessary support structures where required. The combined printing time of the phantom body and lids was approximately 33 h. To minimize difficult-to-remove supports, the cylinder halves were printed vertically. **LINK TO PUBLICATION:** https://www.mdpi.com/1424-8220/24/4/1226