I will be using:
123D Catch, which is software made by Autodesk that you can download as an app.
Meshmixer, another Autodesk program that is used to clean up my catch.
123D Make, also free software by Autodesk.
Step 1: Do the Catch
When doing the catch you are to take approx. 40 pictures of your thing, in this case my pineapple. You can do this in any way. Either circling around your object, or taking pictures in random order, but try to get at least a couple pictures of each side and of all undercuts that your object might have. This might take a couple tries. Take the pictures using the 123DCatch app. It seems to work better on ipads than on iphones, but it is supposed to work on both.
Upload your pictures and export it up on to the community. Then transfer to you computer.
Step 2: Get Your Catch
Download your file.
Also download Meshmixer.
Step 3: Clean Your Catch
This means deleting any surface that the project has been situated on, and filling out any holes that have occurred. You simply mark the parts that you do not wish to keep, and then delete them. By moving into "Inspector" you can also fill out any holes and correct any inconsistencies.
Disclaimer: This is not a Meshmixer tutorial, so I will not further explain how to clean up your project.
Step 4: 123D Make
I chose to print my pineapple as hollow stacks and in cardboard. You input all info in the fields to the left of you screen and then work your way down through the options.