The Completion of Parshas Vayekhel
The Izhbitzer Rebbe zy”a (Sefer Mei Hashiloach) writes that Parshas Pekudei is a continuation of Parshas Vayakhel, as the details of the usage of the vessels of the Bais Hamikdosh are not stated in Vayakhel, but they are said in Pekudei.
He goes through each one and shows how the Torah does this: In Vayakhel it says how to make an Aron, but it doesn’t say what it is used for. In Pekudei, it says to place the luchos into the Aron. In Vayakhel, it says how to make a Shulchan. In Pekudei, it says to place the lechem hapanim on the Shulchan. In Vayakhel, it says how to make the Menorah. In Pekudei, it says how to light the neiros. In Vayakhel, it says to make the Mizbeach Hazahav. In Pekudei, it says to offer the Ketores upon it. In Vayakhel it says to make the Mizbeach in the Azarah. In Pekudei, it says to place the Olah upon it. In Vayakhel, it says to make the Kiyor. In Pekudei, it says to put water in it to be used for washing.
He says that this is why this Parshah is called “Pekudei”, as the word “nifkad” can mean to fill something that is missing, and Parshas Pekudei fills in the details that are missing in Parshas Vayakhel.