(Currently Only the single barrel version has been tested and only with a small smoke charge. will test 3 barrel at a later date)
Step 1: Construction of the housings and bases.
Next cut out a square bigger then then 3barrels and draw around them carefully with a pen,cut out the outlined part x2 with two piece of card and hot glue them securely with lots of glue,next the bottom part again draw around it and cut out holes in the center of each of the 3 barrel placements,for wires much later in the construction,see pictures.
Fix your barrels in place no glue yet just so you know where they are and the angle you desire them at,mine at a very slight angle for firework mines etc,take a spirit level and make sure its level or at whatever angle you desire it at.
Form corners and sides from thick card,and apply braces to connect box to the part that holds the barrels in place,continue to layer and glue card around it leaving an large opening on the rear side,side with one barrel not two,this for access and electronics placement plus maybe weights to keep it steady now glue the barrels in the permanent place with much glue,once done,i painted it in a thick layer of paint multiple times,then repeated this process with the single barrel version make a box paint it until it the same as the other,now
You will need glue gun and some glue,a push button switch,some wire and optional crocodile clips for the ends,plus some paint for when its done.