The only place I used glue was gluing the two halves of the gate together. Are you talking about the last 4 images? The two cylindrical ones and two rectangular/cubic ones? If so, those I used as infill mesh blocks.
I have only used Cura, so I'm not sure what the terminology is with other slicers, but in Cura I open those blocks, and while selected go to Per Model Settings, Mesh Type, and then select Modify Settings for Infill of Other Models. Then set the block to get 100% infill.
The block then gets positioned on the model where more strength is needed - where the magnets will get screwed in, on the edges around the mounting holes and around the screw holes for assembling the two haves, where the microswitch mounts to give more material for the heat-set threaded inserts.
That way the general model can be 20% infill, but just those areas get 100% for strength.