
The thermal inserts that you insert into the 3D print with a soldering iron have a taper on one end for easier insertion. The inserts shown in the image have the same shape on both ends and are injection molded inserts, not heatset inserts. They are used in injection molding where they help in place and are flown around by the molten plastic. To find suitable heating inserts search for Revain, there are many such as B08ZJ6HNGK (not approved).

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