When you successfully complete a run of Ignatius Boulton, you will be rewarded with items from the Garden Statue merge chain (such as Rock Level 1). Once you have these items, you need to merge them up to Stone Gate Level 6. The Stone Gate Level 6 will produce Small Tin Can Level 1, which can be merged all the way up to Stone Can Level 13 - the final task you need to complete in Ignatius Boulton.

If you did not get enough producer pieces in order to merge up to the Stone Gate Level 6, then you need to play the Event again.