Creating correct shape lense to fit into Assembly

Hi

I am new to solidworks, and appreciate the help!

I have created the black part, shown below, with the holes in it using "surface loft" and "thicken". I would like to create lenses that fit perfectly into the holes ( which are irregularly shaped due to the curve of the part ). I have created a lense of the right diameter, as a new part (shown hovering above a hole below), however I cannot figure out how to get it to curve and fit the hole perfectly.

I have been able to use "filled surface" and then "thicken" to fill the hole exactly, but I am unable to isolate this filled bit and turn it into a seperate part.

Please help me figure out how to make seperate lenses that fit the holes perfetcly

Many thanks!!

SolidworksAssemblies