What do you use for step-ups?

Hi,


I'm working my way through NROLFW (Stage 2) and I split my workouts between home and the small gym we have at work. At home I use my coffee table for the step-ups, but as I've been adding more weight the table seems to be starting to complain a lot. It's not especially expensive or sturdy so I'm starting to feel a bit nervous! At the work gym, I don't have anything high enough to use for step-ups. The bench we have is one of those adjustable height ones and it doesn't lock very securely in place, so it's not safe to step up on. I've been looking at aerobic steppers but they all seem pretty low. I've been substituting leg curls instead.
Does anyone have any ideas for solutions? I don't think my boss is averse to spending a bit of extra money on the gym as long as it's within reason. Alternatively, are there any other exercises that would make good substitutes?


Please help.

I didn't find the right solution from the Internet.

References:
 forum.bodybuilding.com/showthread.php?t=132839963
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Thanks