Can you move the `before_save` line and `attr_accessible :filepath` into the S3File module to reduce duplication? Those can be defined via the `included` method, e.g.

```ruby
def self.included(base)
  base.send :attr_accessible, :filepath
  base.send :before_save, :strip_path
end
```

I believe `attr_accessible` and `before_save` are protected methods, so you have to use `send` to get around that.