MoldiBlocks

Why build it?

Commercial silicone molds for tissue microarrays are expensive and limit experimentation, particularly for smaller or early-stage research projects. A PhD researcher at UC Davis asked whether a lower-cost alternative could be fabricated using accessible tooling. MoldiBlocks began as an effort to reduce the cost of TMA workflows while developing a repeatable approach to fabricating reliable lab-grade silicone molds.

System concept

MoldiBlocks uses a reusable SLA-printed master mold to cast flexible, platinum-cured silicone trays compatible with standard tissue core dimensions. The master is fully post-cured prior to casting to prevent silicone inhibition. Platinum-cure silicone is then poured, degassed, and demolded to produce a reusable tray suitable for repeated experimental use.

Tools & materials

• Shapr3D for CAD
• Elegoo Saturn 2 (ABS-Like V3 resin, transparent)
• Let’s Resin 15A platinum-cure silicone rubber
• EZ Release mold release
• IPA wash station and UV cure station
• Syringes for controlled pours
• Vacuum chamber for silicone degassing

Early learnings

• Post-curing is critical: Residual uncured resin inhibits platinum-cure silicone crosslinking. Extended UV curing followed by warm-air drying is required before casting.
• Degassing improves geometry preservation: Vacuum chamber degassing significantly reduces trapped air and improves feature fidelity compared to syringe-only filling, particularly in narrow core bores.
• Fill strategy matters: Controlled filling combined with degassing yields more consistent core geometry and fewer defects across the mold.

Current Status & Next steps

• Actively testing molds designed for 2 mm tissue cores, with plans to expand to additional core sizes.
• Iterating on a second-generation master with refined tolerances and improved demolding behavior.
• Validating durability through repeated paraffin wax pours.
• Exploring silicone pigmentation to visually distinguish silicone molds from paraffin blocks during handling.
• Investigating removable trays or ejector mechanisms to reduce mechanical stress during sample removal.