How can I make an inexpensive bucket of flowers in a vase for a big round table
Do you want real flowers or artificial ones? Real ones will need water. Pick out your bucket so you can determine how high the flowers need to be to show above the bucket. Then find a container that sits inside the bucket if you are using water. You can cross tape in a grid pattern on top of the vase to help the stems remain upright. If you are using artificial flowers, you can secure them with green floral foam by attaching the foam to the bottom of the bucket to hold your stems
For a large bucket, you might want to put something heavy in the bottom and add a second bucket inside the first one for more height and stability that is smaller. I've used stones, bricks etc. to get that weight. With the outer rim of your bucket holding some of the stems and the taller bucket holding the stems you want higher, it should be gorgeous.
My answer on your other post of this question was for “bigger” than a vase.
I would go to thrift shops & look for vases or something that could be repurposed as a vase.
I would make sure it’s bottom heavy and has a wide base, so that the flowers won’t tip it over.
Maybe you could get the same look by using several vases and fewer flowers. A big bucket of flowers (unless you have access to a garden) can be very expensive and flowers die. I remember a party a friend had once and on the beautifully clothed table, was a pile of dirt with flowers coming out of it. It was a knockout. This was a table for a ladies party where we just had desserts. the impatiens are placed in dirt covered with moss from my yard.