Tip: Layer 3 backgrounds and tides disappear when you hit a message box, so unless you apply this fix, plan your level around that. For example, you can add a sublevel without layer 3 at the start/midpoint, and include your message there.
Replace the global graphics in SMW, like pipes and question blocks, with graphics that I drew, and think are prettier.
These graphics are mostly one-to-one replacements for SMW things, with the exception that I replaced the bush with some extra tiles I think are more useful - a mushroom platform, wide cloud, vine end, etc.
Swapping out one of the files lets you replace the diagonal pipe and climbing nets with some SMB3 stuff.