The only thing that convinced Harry to get out of bed the next morning was the abundance of owls flying around his hotel room. Upon returning late in the night, he had stumbled over to the balcony and opened the door, hoping that the delivery owls expected in the morning would drop off their packages and be done. It didn't seem to work that way, however. They wanted his personal attention.
Groaning, Harry climbed out of bed and began untying the packages from their respective owls. Thoughtfully, he reflected on the semi-success of the phoenix fire transportation spell. He had been able to physically appear in the Chamber of Secrets, almost as if he had found a way to penetrate the famous apparition wards of Hogwarts. The downside was that it had left Harry completely exhausted. Bellatrix had theorized that it was because he had performed the phoenix fire and image projection spells simultaneously. She seemed to think that it would take Harry a lot less energy to transport himself once he could perform the phoenix fire spell without the image projection spell.
In the end, Harry has been so drained, that he had only been able to use the image projection and phoenix fire to get himself beyond the Hogwarts wards. From there, he had been able to apparate to his hotel room where he had climbed into bed and passed out.
Once the owls were relieved of their burdens, and their packages were spread across the room, Harry ordered breakfast from room service and took a shower. After his shower, he ate his breakfast and then moved onto handling his packages.
Harry unwrapped and opened each of the eighteen strongboxes as well as the cases containing the potions he had also bought. Methodically, he began dividing the potions equally between the strongboxes. Once the potions were gone, he dug out the case of wands and put five wands into each strongbox. Once the strongboxes had equal amounts of potions and wands, he retrieved a bag of money and liberally filled each box with both Muggle and magical currency.
At this juncture, Harry packed his possessions, shrunk his trunk and checked out of the hotel. Under a basic magical disguise, he proceeded to a large, Muggle toy store in London where he began wandering the aisles, looking for a specific product.
"Can I help you?" came a young man's voice.
Harry turned and spied a young store employee looking at him expectantly. "Yes," Harry acknowledged, "I'm looking for a Rubik's cube. I'd like to buy eighteen."
The employee looked dumbfounded. "A Rubik's cube?" he asked. "I've never heard of that."
Inwardly, Harry cursed the inconvenience of time travel. The puzzle probably had yet to be invented. On the other hand, the store clerk could very well be ignorant. "It's a puzzle cube," Harry explained. "It has lots of cubes that you can turn and with different colors."
"Oh," said the clerk, "a magic cube!"
"Of course," Harry said, "that's precisely what I meant." He reflected on how fortunate it was that the Muggles would never suspect time travel based on that slip.
Ten minutes later, Harry was the proud owner of eighteen magic cubes. From the Muggle toy store, he made his way to a new hotel in a less-busy part of London where he unpacked his possessions. He lined up the strongboxes on the floor next to each other. He then removed each magic cube from its packaging and lined them up on a desk. He fetched himself a glass of water and sat down at the desk in front of magic cubes. Setting the water glass on the table, Harry drew his wand and began his effort to replicate one of Hermione Granger's more ingenious creations-the multi-destination portkey.