The best way to make a 3D muscular system model would be with Computer Aided Design (CAD) software. Often used in architecture, this software would enable you to generate a model human body and graphically design the muscles onto the frame; adding the vascular elements as you go along. Of course, this way, while it might look more impressive, would be quite demanding of time and skill if you didn't fully comprehend the work at hand.
Alternatively, you could make a real-life model. This will also take time though. You will need to twist two hook screws into a tennis ball, arranging them on opposite sides. You will then need two PVC pipes. Drill two holes into one end of each, making sure the holes are on opposite sides. You then twist the hook screw into each drilled hole. At this point the ball will be in the middle with hook screws coming out of either side of it. They will each be screwed through two holes in a piece of PVC tubing.
Now, hook a bit of bungee cord from the end of one pipe to one of the ball's hooks. Do the same for the other tube. You will now inflate a balloon to 1/3 full. You will bend the structure so it's at a 90-degree angle, and place the balloon into this bent section. Tape the ends of the balloon onto the PVC piping and there you go; just stretch open the structure and your balloon 'muscle' stretches too. Bend it back and it contracts.
Alternatively, you could make a real-life model. This will also take time though. You will need to twist two hook screws into a tennis ball, arranging them on opposite sides. You will then need two PVC pipes. Drill two holes into one end of each, making sure the holes are on opposite sides. You then twist the hook screw into each drilled hole. At this point the ball will be in the middle with hook screws coming out of either side of it. They will each be screwed through two holes in a piece of PVC tubing.
Now, hook a bit of bungee cord from the end of one pipe to one of the ball's hooks. Do the same for the other tube. You will now inflate a balloon to 1/3 full. You will bend the structure so it's at a 90-degree angle, and place the balloon into this bent section. Tape the ends of the balloon onto the PVC piping and there you go; just stretch open the structure and your balloon 'muscle' stretches too. Bend it back and it contracts.
