Most of his strings are + or neutral on block.
My favorite frame traps/mix ups I have made so far are:
The F+31 loop, it has a natural delay to it, so it's a frame trap. You can stop the F+3 and not do the one, and do many other options.
Off the top of my head you could do:
Continue the F+31 loop into command throw, which may be + on block and is 2 natural delays in one string.
Do another F+3
Go into a D+3
regular throw
Continue F+312
My other favorite string to do this is 112, he has a delay between the last 1, and the ending 2. So you could do the same mix ups above.
One more thing, a meaty jump in kick is a frame trap/mix up as well.