Can't knit the surfaces

Hi Claudia,

first hide all bodies to easier review it. You have one surface that is not needed! Use "filled surface" to close the sides then knit to a solid. At end use "combine" feature to merge all bodies together.

Hope that helps!

Here your file but I can't make a solid combine because some errors on surface see the final result

Here overlaping you must fix 2 places first Knit all and combine

Edited: