Invention Name:BARDIS (Books And Relevant Dimensional Insertion Spell)
The crowning achievement of high energy magic,a craft which allows travel in almost any dimension including time.Its mechanisms are complex so will be examined one at a time.
Firstly its exterior,as will become apparent,is very a different thing from its interior.Outside it is a small wooden booth which has several spell books built into its walls,one of them contains a semi sentient spell which senses the craft's surroundings and uses shape changing magic to turn the booth into an inconspicuous object.Please note that this chameleon spell as it is known is prone to error and will often break down entirely,during tests for some bizarre reason the craft ended up stuck looking like an Ankh Morpork city watch box.
The second exterior spell warps the very warpable fabric of space to ensure that inside the booth is as big as a large room,it is of course much much larger than this one room but we can't talk about that because of budget cuts.From here the craft can be controlled using the circular control panel in the centre.
What follows is an explanation of how the craft flies,the controls on the panel are used to signal the small stack of sentient spells in its core.A very powerful teleport spell is used to transport the craft and its pilots into the winding infinite library that is L-Space,from here lesser levitation spells can be used to pilot it through the corridors and bookworm holes to any location in the multiverse and at any time.Throughout this process the spells indicate their understanding of what you want them to do by spasmodically levitating a crystal column in the centre of the control panel.
Notes:Because of the risk of materialising in a universe which lacks sufficient magic(it sounds crazy but believe me they do exist),several gigantic Thaumus® flasks are built into the ship which act like fuel tanks.Simply materialise momentarily in an area with a high magic concentration such as gnarly ground,open the tanks and let them fill with thaums.Close them up and you can carry a magic supply with you.
Also do not attempt to open the control panel to read the spells for yourself,doing so will result in an unpleasant death after several moments as an all powerful demigod.Alternatively you may turn into an egg
Proof that L-Space exists in this universe
Fact 1:Heavier things distort time and space more
Fact 2:A page with ink on it is heavier than an unprinted page
Conclusion:A book distorts time and space more than blank papers