Warping Z-HIPS

Just printed this self-designed Samsung Charger Stand. Result is basically great but the object is deformed due to warping I guess. The marked part lifts up from raft almost 1mm. Very ugly.

Somebody knows what to do? I already had not much infill and fan turned off.

I did this with Z-HIPS... I'm trying now with Z-ULTRAT and the External Material settings... let's see how this works... but Z-HIPS should me the material with the lowest deformation right? Little frustrating...

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Thanks a lot for any help

The warping is almost the same with all materials I tried... we need Z-PLA pretty soon :)