The Dice Train

A number of dice making a train with an engine and funnel
Dice joining with the rule of same-ness ie. four facing four.
The top of the funnel must equal the addition of 2 or more carriages (dice).
If 1 or 6 facing then possible ‘tops’ are 2, 3, 4, 5     a
If 2 or 5 facing then possible ‘tops’ are 1, 3, 4, 6     b
If 3 or 4  facing then possible ‘tops’ are 1, 2, 5, 6    c