My trap dipole exists in the form it does because, like many of us, the garden is too small. However, these dipoles are fairly predictable and not too hard to make.
The one page plans for this one came with the second hand TS530 I bought, along with the dipole itself. By the time I got it home and looked at it, it was a real mess of tangled wire. Some of the soldered joints were dry and the traps looked grubby and full of cobwebs. I was grateful however not only for the traps to see how they were made but for the iron pipes which made a mast..
Since I had the dimensions and some RG58 I made another trap dipole for 80/40/20 from scratch. It works very well.
The call W3DZZ is seen on the plans page I have, so that is where the credits might belong.
It has worked well for me - still does. Like most trap dipoles it is fairly narrow banded.

For now - here are the measurements.  Click the pic for a bigger views.

Both  traps are wound on a 43mm diameter former using RG58 coax.

The 7Mhz trap is 10.5 turns on a 120mm length former.
The 14Mhz trap is 5.5 turns on a 70mm length of former.
My drawing on the right shows about 8 turns. The GDO will be working overtime!
Someone elso can tell you whether to use a balun or not.
I use one because I happen to have one, it works well without.
The holes in the tube for the coax should be a good fit. A HOT soldering iron is best for joining up the wires. I use an 80 watt iron with a 1/4" chisel tip on it. "Big Iron"!  The joins need sealing with your favourite sealer. I use silicon rubber sealer. 'Seem ok.
Who am I to say how to build a dipole.......?