If you do a Google search for "40k barbed cable" you will find lots of matches. There will also be several videos. Perhaps the scale of the wire being made too large, or the barbs looked untidy, or the method indicated took too much effort to make a reasonable amount.
However, there is at least one great technique you can improve a little on. However, one important thing is that you don't add any spines. On the Warhammer 40,000 scale, the thorn was only 1/60 the size of an Imperial Guard soldier. That's not enough to worry about.
Image Source: Google
A great Google search is "barbed wire defense positions" in image mode. You'll see some great examples of how barbed wire can actually be used. Barbed wire has been used in the past to improve guard positions.
It performs a specific function to target, protect or engage. Correctly placed barbed wire can propel attackers along a specific route, ultimately increasing the defender's firepower effectiveness (for example, attacking attackers in a minefield).
It can be used to protect defenders through fences or barbed wire trenches, which make it much more difficult to get over fences or enter trenches.
And they can be used to engage defenders often right in front of the grenade launcher to slow them down or deny terrain. After all, this is an obstacle that an attacker can overcome. However, this left the attacker exposed to defensive fire for a long time.
Later in Warhammer 40k, it is recommended that, using barbed wire in two ways – attachment and defense. Attachment must be an open field which is seen as a difficult one.
Since the site is open, units will not receive any protection compensation unless they go down. A good size might be 4 inches by 8 inches.
Barbed wire protects other terrain trenches, barricades, force, or whatever. Defenders use any terrain – usually, 4+ or 5+ saves protection. However, attackers have to put in tough tests on the pitch, enough to attack defenders.