Stuff
"Wait a moment, Father."
The Doctor glanced over his shoulder, his silhouette framed in the light of the door.
"Jenny, has that bag fallen open again? I told you not to overstuff it. There's only so much a bit of denim fabric can handle you know." He turned to watch Jenny repack the denim satchel she had taken to wearing. A small box, several cans, a blaster, a knife, a roll of gauze and several different kinds of currency were stuffed back inside the bulging bag. She pulled the long strap over her shoulder, letting it fall bandolier-style across her chest. The bag thumped into the small of her back, and something fell out of it with a clatter. She grimaced. The Doctor rolled his eyes.
"Here. Take the bag off. This is long overdue."
"What?"
"Just take the bag off."
Eyes wary, Jenny pulled off her satchel, handing it over. The Doctor took it, and pulled out the items she had in it one by one.
"Oh, that's nice. Where did you get that? Do you need to carry this? And this? And-no, actually, that's probably something good to have on hand with you around. But these?"
Finally, her bag was empty. The Doctor shook it just to be sure, then pulled it open.
"All right. Now we're ready. All I need is-" He jumped up, pulled a grate from the floor, found a crate and dug through it. After a moment he came up with a small object, something like a nautilus shell.
"Ah! Here we are! Trans-material expander. This'll help quite a bit."
"For what?"
He grinned. "For a bit of extra room in there. Expand a plane inside, tie it into the fabric of your bag, and viola! Instant roominess."
He placed the tool on the bottom of the bag, playing his fingers over the ridges of the shell. His eyes grew intent as he focused on the work he was doing, as the small shell began to glow. The air around her satchel shimmered like a heat-mirage. Then the Doctor took a breath, and smiled.
"There we go!" He reached into her bag-up to his wrist, then up to his elbow- and pulled out the expander. "Bung your things in there now."
Jenny nodded. She picked up her bag, hefting it tentatively. It felt the same as ever. Stepping over to her necessities, she dropped them into her bag one by one. The bag didn't expand. Even when she added the towel and the book on dimensional engineering, it stayed the same. She glanced up from it-and grinned.
"You have got to teach me how to do that."
The Doctor smiled. "What do you want some more space in?"
Jenny considered for a moment. "Jeans with pockets that are bigger on the inside. Can I try that?"