This is something I got in my head & tried out with my sister's family for a Father's Day gift for their dad. We were hanging out one afternoon & we gave everyone a part and it was done lickety split.
-Pick out a shell to represent each person in your family
-Paint your canvas & you can add glue to the border and sprinkle sand or crushed shell (I had crushed shells). I added a simple paint border inside the shell border.
-If you don't have a canvas, you can use a piece of wood
-If you have letter stamps, do a single initial to represent each family member or like this: "mom, dad, MM, M, E". No letter stamps? Then just write the names of each member below the shell.
If you wanted to add color to the project, everyone could paint their own shell.