It looks like you've got his toes tied to the stocks, leaving his feet extra vulnerable to a good tickle or, perhaps, the cane. Either of which could be made more exciting by attaching some nipple clamps to those white strings so that any time he moves his feet or even just his toes, he gets a nice tug on his nipples.

And, of course, his hole is just begging to be filled. I think I'd go with something that vibrates. Keep it on a lower setting so it teases him and makes him squirm, once again pulling on his nipples any time his feet move.