PROTOBLOCK is a new composite material made of inorganic granules and epoxy resin engineered to form a micro-porous structure for use as prototype vacuum form or thermoform tooling. The material is air-permeable over the entire surface allowing for unique design considerations for prototype tools. PROTOBLOCK is a cost effective alternative to other permeable materials when considering short duration runs.

PROTOBLOCK may also be used in vacuum clamping devices. Even clamping is attained without the need for drilling. Since there are no drill holes or channels, even sensitive parts show no deformation. Static jam while ejecting can be eliminated using compressed air, which creates a smooth and even air cushion.

Physical properties at 67°F (20 °C)

PropertyValue (Eng)Value (SI)
Density106.1 lb/ft31.7 g/cm3
Hardness Shore D8080
Flexural strength3,192 psi22 N/mm2
Flexural Modulus1,190 ksi8,200 N/mm2
Impact strength1.52 ft-lb/in23.2 kJ/m2
Coefficient of thermal expansion
25 °C -125°C (77 – 257 °F)
14 -16 x 10-6 in/in/°F25 – 30 x 10-6 mm/mm/°C
Thermal conductivity:
at 100°C (212 °F)
0.86 BTU/ hr-ft-°F1.6 W / m-°C
Martens Dimensional Stability150 °F65 °C
Total porosity (by volume)20%20%


pdf METAPOR Machining Guide (PDF)
pdf METAPOR Mold Construction Guide (PDF)

Users report the following advantages:

  • High Definition and Accuracy
  • Faster Air Evacuation
  • Improved Surface Quality
  • Reduced Machine Time
  • Trapped Air Elimination
  • Improved Mold Detail

Available Sizes
PROTOBLOCK is manufactured in blocks of 500 x 500 x 400 mm, (~20″ x 20″ x 16″), and cut into slabs of any required thickness. After the cutting process, the air permeability of the slab surface is reduced due to partial closure of the pores. It is essential to mill both surfaces of the slab by cutting off approx. 0.5mm, (0.02″), providing complete air permeability.

Store dry, protect against jolts and impacts. Avoid contact with grease and fluids.

The machining properties of PROTOBLOCK are excellent and are comparable with rapid machinable aluminium. PROTOBLOCK must be machined dry and should not be in contact with any cooling liquids. In order to avoid any closure of pores, appropriate aluminium cutting tools must be used.

Grinding and polishing of the machined surfaces can be made by hand or with a vibrating grinder. Use corundum paper with grains of 400 / 600 / 1200 in the ascending order. PROTOBLOCK has to be polished dry and without any polishing paste!

Air Flow Rates
The numbers are average values for calculating air consumption for overpressure or under pressure applications. Specification is in liters per minute per cm2.

Pressure difference in bar (psi)Plate thickness (mm)Plate thickness (mm)Plate thickness (mm)Plate thickness (mm)Plate thickness (mm)
0.2 (2.9)0.420.350.310.260.23
0.3 (4.4)0.530.440.380.340.30
0.4 (5.8)0.650.550.480.420.37
0.5 (7.3)0.770.650.570.510.46
0.6 (8.8)0.890.750.670.590.54
0.7 (10.3)1.010.870.770.670.62
0.8 (11.6)1.150.990.870.790.71
0.9 (13.1)
1.0 (14.5)1.421.221.080.960.90
2.0 (29.0)2.532.201.971.791.65
3.0 (43.5)3.453.022.722.482.28
4.0 (58.0)4.253.733.373.082.85
5.0 (72.5)4.924.343.933.603.34
6.0 (87.1)5.484.844.394.043.75