The better air flows through a thermoforming tool, the higher the final part quality. By adding air holes to a tool, you can create parts or molds with higher degrees of detail and prevent air bubbles.
By adding air holes, the air gets sucked into the cavity. Without the air holes, there will be nowhere for the air to escape which will result in poorly formed mold. Make sure the holes are small enough so they don’t affect the mold, tiny 0.5mm air holes or as small as you can.
You can read more about how to design tooling for optimal forming quality in tool design and creation .
https://www.youtube.com/watch?v=RNHyEtR-xYM
It’s best to work with tools made from a material with a melting point greater than that of your sheet material, ideally greater than 100°C.
If your tool melted in the FormBox, we suggest reprinting the shape with thicker walls or, if the tool is not for an end part and you are in the early stages of prototyping, you can improve the 3D printed structure by filling the printed tool with plaster to give it extra strength like in this YouTube video:
https://www.youtube.com/watch?v=OZNXWHWMmbI
The number of objects you can fit on the forming bed really depends on the height, width and shape of the objects you’re trying to mold.
Placing multiple tools or design features too close to each other can lead to webbing during the thermoforming process. To avoid that, consider leaving a gap greater than the height of the tallest tool or design feature.