This base works with Mini Splitter v2 for MMU2+1s mod by Ryper3D | Download free STL model | PrusaPrinters or Mini Splitter for MMU2+1s mod by Ryper3D | Download free STL model | PrusaPrinters.

I have the Bondtech Upgrade Kit for Prusa i3 MK3S Mosquito Fit. The current mini splitter base will not fit on this Bondtech. 

I started with Bondtech_Prusa_i3/Sensor Cover MK3s.STL at master · BondtechAB/Bondtech_Prusa_i3 (github.com) and modified it in Tinkercad.