Wanted to incline the HD6 up, but the wobbly sheet metal parts were no good.  This is a solid base which can be filled with sand and inclines at 9 deg.  Option to use a plate of steel to close it off.  A Kanto stand top plate was reused in my case.  Two models are uploaded: one with the Kanto outline and one blank.

The cylinder solid in the model with the Kanto plate can be used to enforce no support or top layer to allow filling, to be covered by a top plate.

The part fits on an X1, but the orientation makes the angle very shallow.  It was worth the extra material for me since the front layer lines are most important and the others are hidden by the speaker.