embeding magnets

Just started learning onshape about 4 days ago.  I am designing a box 100mm x 200mm x 50mm high x 4mm wall with cover.  I made a box 50 mm high, 10 mm top 40 mm bottom of split.  My magnets are 8 mm x 2 mm, actually 1.73 mm thick.  I made two a planes 1mm above and below the split.  Put 4ea  4.15 mm rad circles on both planes. Extruded circles 1.25mm below plane and .5mm above plane for the bottom part and 1.25mm above plane and .5mm below for top part.  I figure this will give me two layers height .25mm ea(50mm total cover over magnet) above magnets when I print.  Did I figure this the right way?  Only thing it is difficult to see the extruded hole inside the box.  I can see the bottom of the hole at 1.75mm but not the top of hole at .5mm  I love this cad design program.
https://cad.onshape.com/documents/893001cfdff4d1fd7ddaffe3/w/40c151a1e77c542a22a803cd/e/c6074752ee95e09439c01323?renderMode=0&uiState=65c77210ddb73847321cab5a