How to Reach Room 46
The Brass Key, Telescope Lens, and Architect's Diagram in context.
Read the routeBlue Prince Items & Keepsakes
Every item in Blue Prince, sorted by how long it lasts. Three buckets: day-bound consumables, persistent items, and permanent keepsakes. Knowing which is which lets you plan multi-day strategies confidently.
Day-Bound Consumables
Lost when the day ends. Use them or lose them.
| Item | Source | Effect |
|---|---|---|
| Steps | Pantry, Kitchen, Conservatory | Currency for crossing doorways. Resets to 50 daily. |
| Gems | Mine, Storeroom, gem chests | Pay for room placement. Reset daily unless stored. |
| Keys | Locksmith, drawers, Vault | Open steel doors. Reset daily. |
| Coins | Sofas, jars, the Wishing Well | Slot machine, vending devices. Reset daily. |
| Lens Fragment | Library or Reading Room | Crafting component for Telescope Lens. |
| Optical Frame | Lab | Crafting component for Telescope Lens. |
Persistent Items (Survive Day End)
Carry across days within a save. Most are gated by puzzles.
| Item | Source | Effect |
|---|---|---|
| Brass Key | Mine layer 3 | Opens Room 46. Costs 6 Gems total to descend. |
| Telescope Lens | Workshop crafting | Required to use the Observatory. |
| Architect's Diagram | Observatory puzzle reward | Reveals Room 46 door location. |
| Pool Cue | Billiard Room reward | +5% chance on Dartboard. Used in Workshop crafting. |
| Deed Paper | Vault interior | Marks the first Room 46 condition met for the day. |
Permanent Keepsakes
Saved to the file forever. These are what create progression in Blue Prince — a roguelike where the player's knowledge + a small set of permanent items defines the meta-progression.
| Item | Source | Effect |
|---|---|---|
| Master Key | Antechamber | Opens 1 steel door per day for free. |
| Marksman's Pin | First Vault open + Trophy Room | Skip 1 Vault code attempt per run. |
| Crown of Mt. Holly | Cellar (Mine layer 4) | Triggers True Ending when carried into Room 46. |
| Boiler Bonus | Boiler Room solve | +1 Gem yield in Mine forever. |
| Architect's Notebook | Read all 3 Forgotten Wing fragments | Reveals room cards' rarity colors during draft. |
Crafting Combinations
Crafting happens at the Workshop or Lab. Recipes:
| Recipe | Inputs | Station | Output |
|---|---|---|---|
| Telescope Lens | Lens Fragment + Optical Frame | Workshop | Telescope Lens |
| Reinforced Cue | Pool Cue + 3 Gems | Workshop | +10% Dartboard accuracy |
| Polished Brass Key | Brass Key + Lab catalyst | Lab | Brass Key with extra durability (cosmetic only) |
Don't lab the Brass Key without confirmation. The "Polished" version is cosmetic but the Lab consumes the original — and you only get one Brass Key per descent. If a run depends on Room 46, skip the Lab.
Where to Find Each Item — Quick Reference
- Vault Code letters: Den, Library, Office. See Vault code derivation.
- Brass Key: Mine layer 3 only. 6 Gems total descent.
- Telescope Lens components: Lens Fragment (Library/Reading Room), Optical Frame (Lab).
- Master Key: Antechamber chest. First-ever entry only.
- Marksman's Pin: Vault interior on first-ever open, OR Trophy Room reward after Dartboard solve.
- Crown of Mt. Holly: Mine layer 4 (Cellar). Brass Key + 12+ Gems on hand.
- Architect's Notebook: Read 3 Forgotten Wing journal pages in chronological order.
Items FAQ
How does inventory work? Three buckets: day-bound (lost at day end), persistent (survive day end), permanent (saved forever).
What does the Brass Key do? Opens Room 46. Found only at Mine layer 3.
Most important item? Brass Key first, then Master Key, then Crown.
How to craft the Telescope Lens? Workshop: Lens Fragment + Optical Frame.
Are items random? No. Each item has a fixed source. The room they spawn in is randomized per run, but the item list is deterministic.
Related Guides
Antechamber
Where to find the Master Key — the strongest permanent item.
AntechamberAll Endings
Crown of Mt. Holly and the True Ending route.
EndingsAll Rooms List
Where each crafting room (Workshop, Lab) sits in the draft pool.
Room database