If you have the right chop stick, insert it in one of the two holes (depending on what angle you want). Then center your ebook in the groove so it is stable.

This model is nearly fully parametric; I fiddled with it to position things slightly better, so if you change the parameters, it might need readjustment.

Parameters are:
supx, supy : dimensions of the chopstick base (rectangular)
len : length of the base; increase this for greater stability
groove: width and depth of the groove to fit the ebook; make it slightly larger; a tight fit is not necessary

After adjusting, make sure that the support holes are deep enough to hold and the outside walls are thick enough to not break through.

With some care, four holes (at four angles) could be supported, with two off center holes per side. But two angles seems to be good enough.

(Yes, it is silly to put sticks in both holes at once, but it helps show where the holes are in the pic...)

Feedback is welcome.