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Easier - use a flat glass plate to support the secondary, plane parallel to 1/4 wave or better and antibreflection coated ...
Might be easier to pinch a corrector plate from an old SCT... then you could use a spherical primary as well ...
But wait a minute ... this is the whole point of maksutov newtonians - no spider vanes so no spikes at all, all spherical surfaces, fast aperture, no coma and a sealed optical tube to keep dust out ...
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