I bought the Plein Air Pro Watercolor version to serve as both a plein air and studio easel for my vacation home. I like it a lot for my purposes. However, I prefer more paint wells than are provided, so I made a simple modification to some of them by building a dividing wall with hotglue. The protective cover slides partway underneath the palette when in use to act as a catchall tray for small items, such as pencil, eraser, wipe rags, etc. A collapsible water bucket is intended to hang underneath a hole in the upper center of the palette, but there are several problems with this: 1) fitting it on and off the site is difficult because of the length and construction of the bucket’s handle, 2) the handle gets in the way when rinsing out brushes, 3) water tends to drip down the sides of the bucket when brushes are wiped off on the edge (when using it indoors, I keep a plastic sheet and absorbent towel underneath to protect the floor), and 4) the folding buckets tend to split along the folds when they have been opened and closed repeatedly over a period of time. I prefer to simply drop a lipped or tapered water cup in to rest on the edges of the hole when using it in the studio; for outdoors I replaced the plastic handle with a more flexible fabric one.
An optional extra shelf, which is configured to adapt to a variety of uses, includes, among other features, a hole for a tapered container and holes for more brushes (the palette cover also includes brush holes). It works well to hold loose tubes, supplemental materials, or a separate, limited oil or acrylic setup. I haven’t gotten the Plein Air Pro retrofit for oils, since I don’t use them much at that location.
Note: The setup is a few inches too large to fit into a standard backpack, so I recommend ordering the backpack designed specifically for the En Plein Air Pro kit. It’s well constructed and worth the price.