It was definetly hard but well worth it, and I know its secure.
The frame I did actually buy the wood for it as I couldn't get lengths in the right thickness. All I did was use studwork timber from wickes (£2.13 a length) and split it into two, two for the price of one, which made the front and back. The left side where the door is just the same timber but used as whole pieces. The right side was reclaimed wood covered in shiplap, again left over from a friends fence. The roof is used sheets of ply again from a friend and the floor is 20mm thick ply. The roof supports for the ply is actually door frames reclaimed from a wood pile. All the wood got planed down to make it a bit smoother, but its not perfect just good enough.
IIRC this is the cost of the build,
Studwork timber Less than £15
4 lengths of batten from wickes £4
Paint from wilkinsons £7 (pet safe)
30m roll of 1/2 inch 1/2 inch mesh & 30m roll of 1 inch x 1inch mesh £54 (IIRC)
All in all it has cost well under £100 even after you add in the bark, bolts, hinges etc
The best buy had to be the mesh, the 1/2 inch x 1/2 inch cost me £34 I think it was, when I priced it up every where else like screwfix, wickes it would cost over £100. The rool was 36 inch wide by 30 m and was from a company called Hills of Devon, found them on ebay.
All in all it was quite good fun, and I am by no means a carpenter I can't cut a straight edge with a saw to save my life. The only problem is that it is going to take me another month to clear the garden up from saw dust, wood shavings and pieces of cut mesh lol