The laptop project has stalled. I'm waiting for some components to arrive, and I can't order the replacement USB power bank I need, because it's out-of-stock. It's been out-of-stock for over a month now. While I'm waiting, let's have a look at keyboards.
USB keyboards just like your laptop keyboard are hard to find. Touch-pads aren't needed on a desktop, so it's no surprise that very few USB keyboards have them.
I wasn't happy with the original keyboard that I bought (an Adesso AKB-410UB). It works okay, but the touch-pad and mouse buttons are a bit twitchy. It's also thicker than I'd like.
My search led me to Home-Theatre PC (HTPC) keyboards, because they often have touch-pads. I tried out the Riitek Rii K18. It has backlit keys, which are nice. The battery life is rather short, though, and they keys are smaller and closer together than normal. This leads to hitting the wrong keys more often. The touch-pad is too twitchy, registering clicks when you're only trying to move the mouse pointer. However, the real killer for me is that you cannot hold down the right mouse button; it only registers a right mouse click. This isn't a problem on Windows, but on AmigaOS menus are accessed by holding down the right mouse button.
The next keyboard I tried was the Arteck HW197. This one is pretty good. It has standard key sizing and spacing, and the touch-pad works well. Alas, it has some drawbacks too. It's a wireless keyboard without chargeable batteries. The batteries last a few months, which isn't bad, but it's short enough that the lack of rechargeability is annoying.
Current DIY Laptop Keyboard Status
The Arteck keyboard is the best one that I could find. It isn't perfect, but it'll do (unless someone can recommend a better one). Ideally I'd be able to find a keyboard that's just like the one in my laptop, but connected via USB. However, as far as I know, that doesn't exist.
I'm thinking about how I could create a flexible mount for the keyboard, so that it could be easily changed later, should a better one come along. Please let me know if you have any bright ideas on how to make a flexible keyboard mount (or know of a more suitable keyboard).
Why a USB Keyboard?
Basically, to keep things simple. USB keyboards work with everything (unlike bluetooth), and designing a custom keyboard would be a whole project in its own right.
A nice feature of using a ready made keyboard, is that you could detach it when you're at home (or work). That way you can sit comfortably with good posture when a desk is available, or use it as a laptop on-the-go.