You need to make sure that the hollow part contains a large enough escape hole with a hole diameter greater than 2mm so that the hollow part can be cleaned.

If the escape holes do not meet the minimum requirements, it is recommended that you increase the size of the existing escape holes, increase the number of escape holes, or fill the hollow parts.

In particular, when there is only one escape hole, there is no guarantee that the unused material will escape completely.

We recommend using multiple escape holes.