My group and I will be designing and engineering a crossbow. It will be aimed as an educational toy, designed to entertain children while teaching about crank, winch, latch, tension mechanisms, elastic tensile energy, and trigger mechanisms.
Currently, there are three examples to serve as precedents. One is of a winch crank design, while the others are all of a manual load design. 
Out of all the designs, I believe the second is the best. It is both simple to build and functional. The first design, while it may look cool, the winch mechanism would not be a good idea. It would be hard to build and design, and since what is being made is a mini crossbow for children, the draw force of the bow shouldn’t be large enough to require a winch. The third design, while similar to the second, is much more complicated. The second has all the core mechanisms of a crossbow, while being simple at the same time.
The image above is, from my research, the best and simplest trigger mechanism I could build. Simply put, it is two sliding wood pieces connected by a spring. When the trigger (bottom piece) is pulled, the top piece slides out, releasing the string. When the trigger is released, the spring allows the pieces to fall back into place.
To make this crossbow work, I will need to learn a multitude of skills. To make the stock and body of the crossbow, I will need to work with power tools such as the dropsaw or table saw. The trigger will be made using 3D printing, which I have previously learned.
The materials we are planning on using include a large piece of wood, 3D printed plastic, Bamboo or PVC piping, rope, and wood stain.
The first two days of the project should be used to make the initial body of the crossbow (stock, body, and bow) out of a large block of wood. On the third day, when the trigger of above design, designed using Autodesk Fusion, is 3D printed, the trigger mechanism should be built into the crossbow. The third class should be used to polish up the Crossbow, sanding the body down and finishing the wood. The fourth and fifth days are simple contingencies in case anything in the process goes wrong, or doesn’t go as expected.