Then once you have clicked extrude boss/base, you come up with this solid feature. And the reason my cylinder is blue is because i went to appearances and clicked the color i wanted on the body that choose. Now what your gonna want to do is draw another circle on top of this cylinder as seen on my picture,once you've done this you need to extrude the newly added circle. and make the extrude cut go a little less than halfway down becuase your gonna have to do something else explained in the next step.
Step 2: Simple Cupholder
The reason for halfway down, is because you want it to look like what i have. so your gonna have to draw another circle on top of the one you just did that is halfway in the middle of the circle, so it will end up like mine. the soda will fit perfectly in this design, because most cups get skinnier the farther you go down. so i got this as a result.
Step 3: Simple Cupholder
Once you did all those steps, you have one more thing to do. To make it look cleaner, add fillets to all the sides to round the edges out. I used.20 inches on the fillet part.
once that is down, you have successfully created the simple cupholder!