I searched everywhere for a 37.3mm Seatmast topper for the FM028 frame but nothing came up.  I guess that’s the first fallacy in their design.  Without aftermarket support I decided to make my own.  I decided to go with the yoke clamping design as that seems to always be the lightest option nowadays.  The seatmast is quite large, so one of the mounting bolts had come from the inside of the topper or else the distance between the yokes would be too far, putting more stress on the saddle rails.  This forced a 6mm setback which I personally welcomed. 
 
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It turned out to look a lot like the Tune topper even though i did my initial sketches before ever seeing the Tune design.  I guess sometimes there’s only one way (at least straight forward way) of designing something.