A leg up

I have been working on the new project this last weekend.
This is the first look at the new project. It is a 6.5" builders tube the type you pour concrete in as footing for a deck or gate post.
I have then split the one end open so it is a funnel shape at the top. To keep the shape I have cut 'V' shapes then jammed and glued cardboard wedges into the 'V' shapes.