[DeKay]

In Oz we only got the 1 grip in the box, so I've been looking for custom grips for a while.
Found a 3D model online, cant remember where. Loaded it up, added Pentax lettering for added effect.
Its OK but I didn't use it for long, went back to the grip it came with. Turns out I got used to the medium grip.

If you get the battery grip it will add some length and give you a little more grip area. It matches up to the large grip.
...
I use a use a optech wrist stap and let most of the weight hang on my fingers when walking around with the camera.

My thoughts, exactly.

[Robot camera]

As others have suggested, building up an existing grip is one way to go. One material you can use is Sugru, a mouldable silicone rubber: The World's First Mouldable Glue | Sugru

I used it to build a wall around the mode dial of my K20D, to stop the dial being nudged to the wrong mode when I put the camera in my bag. It's been there several years and it's still firmly attached. The finish is fairly smooth, but you could imprint a grip pattern into the Sugru before it sets.

[Grimmus]

This thread is encouraging crimes against the aesthetics of the Kp. Please stop!

[mikesbike]

I am already used to my KP, which is a great DSLR on the whole, and which I've used many years. Still, my old K-30 is steadier/safer to carry in one hand, that is an ergonomic fact.

For me, the KP's concept is a winner. And is the Pentax DSLR answer to APS-C mirrorless offerings. I actually prefer the smallest grip for shooting and carrying with a small lens like a Limited prime, and still ok with the DA 20-40mm Limited. Then the largest grip with larger lenses up to and including the DA* 50-135mm. For carrying. I generally have my trigger finger up over the front wheel housing where it can secure a supplementary hold, while the other 3 fingers are on the grip. In this way, for me, my K-5 IIs is bit better for carrying over the KP's largest grip, but not by much. For yet larger or heavier lenses, like the DA* 200mm f/2.8 or FA* 300mm f/4.5, I prefer using the KP's battery grip, which greatly increases gripping surface, even considerably beyond my K-5 IIs without its battery grip. For carrying, then the vertical shooting position is the most extremely secure. The battery grip can provide a very lengthy battery life, great for shooting events.

The KP is thus the most potentially versatile design, ranging from very compact with small lenses and a counter consideration over APS-C mirrorless designs, but also potentially very capable for larger lens ensembles.

[Sandy Hancock]

I'm 6'3" with big blacksmith's hands. I really like the KP grip, but it does require a different approach. A little counter pressure from the opposing thumb and it's rock solid.

There's a video somewhere in this sub-forum of me juggling my KP one handed, with the DFA150-450 mounted.

[Tsuken]

Coming from a K-30 with its very-deep grip I was initially concerned by the flatness of the KP. I love it now. I don’t actually want to have my fingers flexed and gripping the camera deeply like that anyway. I support it mostly with my left hand, and the right is for driving the dials and buttons.

[bigyinn]

I was lucky enough to get my KP with all 3 grips. Coming from a K50 (and P50, Super A before that) I liked the big grip and thats what stayed on the body. I tend to wrap the strap around my wrist a couple of times to be safe. I tried using a wrist loop instead of a strap, but found it feeling rather unsecure when changes lenses.

[Ex Finn.]

Large grip combined with the battery grip.
DA 11-18 is heavy enough to really benefit from that combination plus the added battery capacity.
Just spent a month in Finland, did not worry about battery life once.