Simulating attacks

Hello everyone.
I got a training dummy for Christmas (a few weeks in advance tho) from my parents so i want to do some training on him. He resembles a human torso, so it is as realistic as possible. It works great to train my attacks on it, but i want more than that.
I'm trying to train simultaneous attack and defense. The movements have become second nature to me when executing it, but to react to my opponents move and to apply that technique, that's what i want to train next. But, i'm having big problems with visualizing the punch. Sometimes i can visualize it good, but sometimes i can't. And the period of when i can't do it, is lasting for about a whole week now. What i was thinking was building something from a few pipes or wooden pieces wich closely resembles an arm, executing a punch. But i have no idea how i should do that.Does anyone have something like this, or anything that would help in making something like this?

And yes, i have someone with whom i can train with, but i don't want to limit myself to the times that he is available to train. AND he's away for 2 weeks.

Oh, and if this isn't the right place to ask this, i'm sorry i didn't know where to put this.

I've used a few training dummies over the years (both rubber and flesh), and the rubber ones are one where your imagination comes into play. Rather than gawking up some kind of "arms", etc. imagine the attack, and use the dummy to go directly to the point of your attack.

Parry or block exactly as if you were fighting, and then drive toward the dummy... concentrating on using your speed to the target and multiplying your hits on the target once "inside". Use the height adjustment to learn to move against people of differing heighths, and try to visualize the problems you will encounter with the targets in different places. Gage your ma-ai (fighting distance) based on their heighth, and that will cause you to naturally adapt to the changes you encounter.

I'd rather have a "live dummy"... but one of the "training Bob" dummies will work just fine if you use your head and your training to learn effectively. Both are merely tools to learning a skill... only the real ones can hit back.

You really cannot practice effective defense on something that does not attack. Sorry.

Work on your attacks with the training dummy.

Might I also include asking your instructor for drills that would help specifically for your style. Maybe he can give you the defense side you are seeking in class; while you practice the attacking with your dummy.