The second half of the femur came off the saw in a clean split. I set it beside the first and held the two pieces together end to end, checking that the flat cut faces would mate properly.

  They did, which was all I needed.

  Each half was roughly as long as my forearm, from wrist to elbow. That wasn't much to work with, but it was enough. The bone was thick, the walls solid—there was material to spare even after I carved out the channels. The insulation test had confirmed what Heston told me. Earth affinity, and it wanted nothing to do with lightning.

  I set them on the bench and picked up my carving tools.

  Hours passed. Small cuts, constant checking, shaving material down a sliver at a time. The interior surface of each half had to be smooth and exact. Any irregularity would create friction against the mechanism, and friction meant wear I couldn't afford.

  By the time my hands started cramping I'd made real progress on the interior channel of the first half. The channel wasn't finished, but the shape was there, the curve consistent, the depth even.

  I set the tools down and stretched my fingers.

  Then I picked up the rib bones.

  The original plan had been clear. The base from the femur halves, the lid from the ribs. The ribs were long, curved, structurally sound, and already proven insulators. Same material logic throughout. No unknown variables.

  I turned one of the ribs over in my hand.

  The base needed rigidity. The two femur halves had to hold the motor and the coil mechanism in place under sustained use—rattling was failure, flex was failure, any movement of the components against each other was wear I couldn't afford. The dense, unyielding bone was exactly right for that.

  But the lid wasn't the base.

  I pressed my thumb into the rib's surface. It didn't give. Not a fraction. This thing had held up the musculature of an earth beast—it was built to resist, not absorb. If someone's sword came down on this lid, or a fist caught it at the wrong angle, the force would transmit straight through to my arm. And if the blow was hard enough, the rib itself wouldn't bend or dent. It would crack.

  I set it down.

  The lid needed to yield slightly. Take an impact, sink a little, spread the force before passing what remained through to my arm. A bruise instead of a break.

  And then I followed that further.

  If the lid sank under impact—absorbed instead of reflected—then anything pressing against it would stay in contact longer. A block, a grab, a shove. Not much longer, fractions of a second, but long enough to matter if the lid was carrying a charge.

  I looked at the rib again.

  Bone wouldn't conduct. Even if I wanted that contact time, the rib would give me nothing but the impact—no charge, no damage beyond the physical.

  Ironwood was different. Ironwood conducted. It also had a grain that allowed it to flex slightly under force without splitting—not like soft timber, nothing dramatic, but enough. The reason smiths used it for high-quality handles was that it didn't shatter on hard blows the way rigid material did.

  If the lid was ironwood, it would take impacts and distribute them rather than crack. It would flex just enough to keep contact with whatever pressed against it. And anything in contact long enough would absorb the full charge rather than the brief pulse of a glancing hit.

  I set the rib down on the far side of the bench, away from the work area.

  The ribs were out.

  I needed ironwood.

  I pulled on my boots and went to the market district. It was still winter-thin, most stalls half-empty, but the permanent shops kept inventory year-round. I headed for the one I'd visited with Hargrave.

  The same clerk was there. He recognized me after a moment.

  "The ironwood," I said before he could offer a greeting.

  He led me to the back shelf. The boards sat where I remembered them—dark, almost black, the grain so tight it looked like it had been drawn with a fine pen. I picked one up—heavy, dense, the grain so tight beneath my fingers it barely felt like wood at all.

  I ran my thumb along the grain. The aether in it stirred the way it had before, reaching slightly toward my fingers.

  I took out a scrap of spider silk from my bag and touched one end to the board, then let a trickle of lightning aether move through the thread.

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  The charge transferred without resistance. Not slowly, not reluctantly—straight through.

  'Perfect.'

  "How much?" I asked, though I already knew.

  "Twelve silver per board. Same as before."

  I looked at the board. I wouldn't need a full board for two lids. A single board, if I was careful with the cuts, would give me both pieces and leave material over for mistakes.

  Twelve silver was steep. A dagger sale gone in one transaction. I looked at the board again. Then at my forearm.

  It was worth it.

  "This one," I said.

  The clerk wrapped it in a cloth and I paid. Twelve silver slid across the counter and I picked up the board and tucked it under my arm.

  Before I left I stopped at the hide stall near the front.

  "River serpent?" I asked the clerk there.

  He checked under the counter and came up with a folded piece—dark green, a faint shimmer to the scales. I unfolded it and checked the size. It was more than enough.

  The scales flexed when I bent it. The hide wanted to return to shape. The scales didn't compress so much as redirect force sideways, spreading it across a wider area—shock absorption, the way Hargrave had described.

  The ironwood would carry the charge. The hide on top would handle impacts and give grip without cutting off what was underneath.

  "Four silver," the clerk said.

  "Done."

  I folded both pieces under my arm and walked back to the tower in the cold.

  The hide had a second use I'd already worked out before buying it.

  The launcher had to attach to my forearm. Metal bands were the obvious answer—forge them, rivet them, done. But metal bands meant weight at the wrong places, cold against skin in winter, and noise during movement. More importantly, metal bands could lead the charge straight into my hand.

  The river serpent hide wouldn't.

  I cut three lengths from the piece—narrow strips, each long enough to wrap around my forearm and overlap slightly. Enough to buckle without coming loose under strain. I scored the edges with a small blade to prevent fraying, then set them aside.

  Three belts. One near the wrist end of the base, one near the elbow end, one across the middle. They'd hold the launcher flush against my forearm without rattling, without shock risk.

  The lid pieces I measured and marked from the ironwood board.

  Two pieces. Mirror shapes, fitted to the curved top of each femur half once mated. I marked the lines with charcoal, double-checked the dimensions against the base I'd already cut, and picked up the saw again.

  Ironwood was harder to cut than the femur bone. It resisted the saw differently—not crumbling, not splintering, just slow. I kept even pressure and let the saw work through it.

  Magnar arrived in the afternoon. He let himself through the gate and knocked on the door with the back of his fist—once, loud.

  "Come in," I called without looking up.

  He came in and stood in the doorway of the living room looking at the bench. Bone dust was still in the air from the morning's carving. The ironwood sat in the middle, cut into two rough lid-shaped pieces. The hide strips were coiled at the edge of the bench.

  "You changed the top?" he said.

  "Ribs were out. Using ironwood instead."

  He picked up one of the cut pieces and turned it over. "This is heavy for a lid."

  "It's ironwood. It's supposed to be heavy."

  "What's wrong with the ribs?"

  "Too rigid. The base needs to be rigid—it's holding the mechanism in place. But if the lid doesn't give at all under a hard hit, it either transmits the full force to my arm or it shatters. Ironwood flexes slightly. It distributes the impact instead of passing all of it through." I took the piece back from him and set it against the matching femur half to check the fit. "And it conducts. If someone presses against the lid—blocks with it, grabs my arm—the contact lasts longer than a brief impact. More charge transferred."

  He turned that over. "So it's softer and more dangerous at the same time."

  "In the right situation, yes."

  He was quiet for a moment, then reached into the bag he'd brought.

  "Got something for you to look at."

  He set it on the bench beside the ironwood.

  It was a chunk of ore, roughly the size of my fist. Dark grey-black, dense, with a surface that caught light in a flat, heavy way. I set down the lid piece and picked it up—heavier than it looked, heavier than something that size had any right to be.

  I turned it over. No real luster, just that same flat solidity. My fingers found a faint grain to the surface, almost crystalline, different from common iron ore or the magnetite I'd worked with before. The specific weight, the color, the grain structure—it was wolframite. Tungsten ore, not refined, not processed, just raw ore, but the origin material was unmistakable.

  I set it down carefully.

  "Where did you get this?"

  "Market, Lyra dragged me out for a walk. Some small merchant had a few pieces out, didn't know what he had. He was trying to sell them as counterweights." Magnar shrugged. "Figured the weight alone made them worth a look. He sold them cheap, said he had no other buyers."

  "How much?"

  "Three copper a piece. I got two."

  Three copper a piece—I nearly laughed.

  Tungsten—once refined—was one of the hardest metals in existence. Melting point so high that most furnaces couldn't touch it. On Earth, it had gone into cutting tools, armor-piercing projectiles, high-temperature components that nothing else could handle.

  I didn't have an arc furnace yet. I didn't have the temperature to process this. But the ore was sitting on my bench for three copper a piece.

  "You did well," I said.

  Magnar looked at me. "It's just a heavy rock."

  "It's tungsten ore."

  "I don't know what that is."

  "It's the ore you refine to get tungsten. A metal that's nearly impossible to melt, harder than almost anything else when alloyed properly, and almost never found sitting in a market stall priced for counterweights." I set the chunk back down. If that merchant had more—if there was a source somewhere in the region that nobody here knew how to use, or if this world simply had no concept for wolframite—the cost of future projects dropped considerably. "Where was this merchant? Which stall?"

  "South side of the market. Near where they sell the dried fish." He glanced at the ore again. "You're going to go buy everything he has, aren't you."

  "Not yet. I need to be able to process it first." I picked up the piece and set it on the shelf above the bench, away from the other materials. "But eventually."

  Magnar watched me put it there. "It really is valuable?"

  "Once I have a furnace that can reach the right temperature, yes. Considerably."

  He looked at it for a moment, then back at me.

  "Good thing I didn't drop it, then."

  "Good thing."

  I picked up the saw and turned back to the second lid piece.

  The electronic components would have to wait—those needed the forge, and the forge needed warmer weather. For now the shape of the thing was enough. The bones, the lid, the hide straps, the serpent-scale cover.

  I started cutting.