The Apollo 13 crew built the "mailbox"
#OTD in 1970: a lithium hydroxide adapter that allows carbon dioxide filters from the Command Module to be used in the Lunar Module. Parts needed: bags, a flight plan card, some hoses, and a lot of duct tape.
go.nasa.gov/4jiuSI4
ALT An interior view of the cramped Apollo 13 Lunar Module (LM) during the trouble-plagued journey back to Earth. This photograph shows some of the temporary hose connections and apparatus which were necessary when the three Apollo astronauts moved from the Command Module to use the Lunar Module as a “lifeboat.” Astronaut John L. Swigert Jr., command module pilot, is on the right. An unidentified astronaut on the left holds in his right hand the feed water bag from the Portable Life Support System (PLSS). Credit: NASA