Saw pumpkin in a growbox as a search result on my listings..
Not sure what the person was looking for, but anyway...
At some point it is in our plans to start developing self contained, transportable hydroponic grow boxes. We are not quite ready for that yet though, so we are currently working on hydroponic systems and working with container plants. Hopefully that will end up yielding pumpkins in growboxes.
Right now it is possible to grow pumpkins in containers. Just takes the right kind of pumpkins to do it. There are a lot of smaller fruit and shorter vine species that can be successfully grown in containers. Some squashes do really well in containers, particularly bush varieties. Some decorative pumpkins and squashes can be trellised, but plants with larger fruits are best left laying unless you can rig up slings to support the fruit to the trellis. Luffa gourds do quite nicely with trellising, and it makes their fruit grow straight- it will tend to curve when grown on the ground.
One can also grow a pumpkin itself in a box to make it grow into a square shape. Instructables has a pretty neat DIY box one can assemble to do it :) There are also several vegetable and fruit shapers available commercially.