Prime Assembler

Test Chamber 13: Place portals as shown to redirect the laser sideways. Use a time portal to move the laser into the future. Travel through the time portal. Rearrange portals in the future so the laser hits the target. Exit the chamber.

Test Chamber 14: Travel to the present using a time portal. Summon a reflector cube and position it in the present as shown to direct the laser into the first node. Use a portal to bring a laser through the first node and into the next two. Travel to the future. Use portals to bring a laser into the present through the time portal, ensuring it passes through the node. Retrieve the reflector cube from the future and bring it to the present via a time portal. Ensure the present reflector cube hits all three nodes; adjust its position if necessary. Return to the future if you moved the present reflector cube. Place the future reflector cube at the end of the nodes to reflect the laser into the receiver, completing the chamber.

Test Chamber 15: Go through the particle field to the left. Place a portal where the laser hits the wall and a time portal on the opposite wall. Travel through the time portal to the future to bypass the particle field. Proceed to the other side of the room and use another time portal to return to the present, now on the other side of the particle field. Place a new portal on the upper wall above the laser room so the laser hits the first receiver. Travel back to the future and place a portal on the small wall in the laser room to shoot the receiver. Return to the present. The laser should still be hitting the first receiver, powering an elevating platform. Stand on the platform and place a time portal behind the node. This will raise the platform, allowing you to summon a reflector cube. Place this reflector cube on the lip above the second receiver. Travel to the future. Retrieve the future reflector cube and enter the laser room. Place a time portal in the laser room to bring the future reflector cube to the present. Position it to reflect the laser into the second receiver through the node. Now, get to the other side of the particle field without going through it (use an existing portal or a time portal). You need to be in the present on the other side. Climb the stairs and place a portal on the upper wall to hit the third receiver. Finally, move the reflector cube onto the switch to complete the chamber.