This is a tricky one. There is a great way to do this, but it is going to take some work. First, you are going to need to visit a local mattress store to get a special part that you will need later on in the process. Select a store that is having a sale, as usually there will be plenty of salespeople on the floor, and you will get helped more promptly. When you find a salesperson, tell them that you want a "twin mattress coupling harness." Don't worry if they give you a blank stare at first, that's only because they don't know what you are talking about. You will have to be patient and explain carefully that you plan to harness your mattresses together to make mega-mattress. After hearing your plan to build a king-sized bed out of two twins, the salesperson is probably going to try and convince you to buy a regular king-sized bed. That is when you know you have him fooled. Pretend to be interested in a king-sized bed, but also mention that you would rather just use the two twins pushed together, so as to save money. The salesperson should have some nice mattresses to show you, but pretend to only be slightly interested. When you feel like the salesperson has put all his cards on the table as far as special offers, free delivery, etc, then make your move. This is the part where you buy the king-sized mattress. You're probably thinking right now "Wait, I don't want to buy a mattress, I want to buy one of those twin-mattress coupling harnesses you mentioned earlier." Stay with me here, we will get to that. Once your king-sized mattress is delivered, you can start the prep-work for installing the twin bed coupling harness. To do this, you will need to bring the twin mattress outdoors, preferably to an alleyway of some sort. Lay the mattresses against some sort of solid structure such as a wall, or dumpster. They will need to rest in this upright position to properly distress the fibers in preparation for the harness. In the meantime, get a few nights in on that king-sized bed you tricked out of that dopey salesman. Once you have made it this far, let me know, and I will give you the rest of the steps. edit: you could also google "twin-bed connector," but I think you will like my DIY plan better in the long run. More on reddit.com

When all else fails, check out Amazon More on reddit.com

Any recommendations on how to solve this center gap issue? We haven’t decided on a bed frame yet, so perhaps that’s a part of the issue. But we are using 2 raze adjustable beds with the wheels locked. But still the beds part in the middle after our 60 pound boxer lays in the “void” ... More on forum.mattressunderground.com

I love my split king. I sleep better and we keep a few inch gap on our adjustable frames. I ruin mattresses and she doesn't.. I bought a 4.6k intellibed midnight and she is still on last year's purple 4 and my old one is in the trash. For sex it kinda sucks but I'd rather sleep perfectly then worry about that. My wife is a crazy sleeper. And now I sleep better without disturbance. More on reddit.com