You will need:
Phillips screwdriver (ETA - Am told by OH that it's a Posidrive screwdriver needed, not a Phillips.
A couple of hours
Cable ties if using as two separate cages
Possibly a soft hammer
Possibly a metal file
1. Stand assembly:
Decide whether you're going to use the stand, or whether you prefer to use the cage without the stand. If you're going to use the stand, push the castors into the plastic caps on the bottom of the stand legs.
2. Take one of the longer sides and one of the shorter sides. The short side needs to go with the small ledge towards the inside of the structure (to support the cage). Fix with the two bolts, then repeat with the second short side. Lie the longer side down with the short sides up in the air, and bolt on the fourth side.
3. Lower level:
You will need to find the correct parts for the lower level of the cage. If you're not using the stand, you can add the castors to the front and back panels at this stage.
The lower front has a pair of doors and a row of holes along the top and bottom.
The lower right hand side has three G shaped runners along the lower edge and two along the top edge.
The lower left hand side has three G shaped runners along the lower edge and three along the top edge. Make sure it's the right way up, with the runners having a right way up G shape profile.
The lower back is one of the big panels with no doors, and has a row of holes along the top and bottom, plus an extra pair of holes which go at the top right.
4. If you're using the stand, position it with the taller side of the stand away from you. The taller side is the back. Put the back panel onto the stand across the back, with the extra holes facing you at the top right.
5. Put the left hand panel into place on the ledge of the stand and butt it up against the back. Bolt the two panels together.
6. Put the right hand panel into place on the ledge of the stand, with the two runner edge at the top. Bolt this into place.
7. Find the base panel. This is an unframed panel with no cut outs.
8. Position the panel so that the bars running back to front are underneath and those running side to side are on top. Slide it into the runners at the bottom of the right and left hand panels until the prongs at the back fit into the holes across the bottom of the back panel.
9. Next comes the middle floor. This is the unframed panel with a corner cut out. Position this so that the cut out is at the back right and slide it onto the runners at the top of the side panels.
10. Next take the front panel with the doors in. Make sure the doors are the right way up and open out of the cage. Offer it up to the front of the cage. It will need to drop down slightly into the stand, with the prongs of the base panel being eased into the holes along its lower edge. Next make sure the prongs of the middle floor fit into the holes along its upper edge. This may take some wiggling to make them all fit. Bolt the front panel on.
11. If you're going to separate the cage into two parts, you need to find the ladder which has two angled ends rather than hooked ends. This fits into the extra holes at the back right and then hinges up to seal the cut out. Fix with cable ties. If you have chewers it may be safer to use wire as well.
12. Upper level:
Find the back of the upper level. This is a large panel with one row of holes along the upper edge. Push the lugs on the bottom corners into the holes at the top of the lower back panel. Try to get them both to go in together, as if one goes straight in it may make the angle wrong for the second lug to slide in. This procedure may require some brute force, a soft hammer or even a metal file. You are permitted to swear at this point.
13. Both remaining side pieces should be identical. Bolt them to the back with the runners at the top.
14. Slide the roof panel into the runners, fitting the prongs into the holes at the top of the back panel.
15. Add the final door panel, making sure the doors are the right way up. Ease the prongs at the front of the roof panel into the holes in the front panel.
16. Bolt the front panel on.
17. Have a cuppa.Useful Mods
The screws which hold the small catches at the top of the left hand doors work their way out. A small dot of Loctite works wonders.
Put a strong magnet on the back of the upper door stop. The ones out of old hard drives are perfect. They stop the doors rattling.
The plastic trays that come as standard are flimsy, easily chewable and do not fit to the edges. If you can afford it, get some metal trays made up.Adding a third floor
It is possible to use a second Explorer to extend the cage to a third floor. The most secure way to do this is to drill out the top corners of the top front and back panels and use a square file on the holes to allow the upper floor of the second explorer to slot on. If you need to do the same thing a second time you will also need some lengths of metal bar to secure a bottom floor onto the top. If these are around 10cm long they will slot into the new holes you've made and sit on top of the bolts to hold the levels together securely.