I know there is nothing worse then your shrink-tube shrinking before its intended purpose and where stripping off allot of jacket isn't an option.
The following steps will show a technique i came up with aiding the problem regardless of space and size.
The tool you will need is basic and may already own: Beau Tech Soldering Aid Tool #SH20A
Substitutes: Jewelers Screwdriver, (larger sizes) , or, Small needle-nose pliers with long narrow nose.
Some notes: I am left handed and you will need to adjust from images.
Avoid using tubing that is the stiff and shinny type, its made from PVC plastics and tears easily for this application. (best is tubing made in USA)
Images were taken while making an XLR microphone cable for concert touring and where failure is not an option.
Soldering technique and shrink tubing are key to any cables longevity, also is proper "under-over" wrapping and individually tied for storage.
Step 1: Strip Wire. Adjust to Desired Length.
Note: The wire shown is 110 ohm for digital transfer and not typical.
Step 2: Tin - Then - Trim
IMPORTANT NOTE and CRITICAL STEP:
Always be sure solder penetrates up and into its jacket when tinning.
Doing this adds strength where its the weakest.
Not doing this is the #1 reason why and where cables fail.
Step 3: Prepare Tubing and Wire
Image 1: Use a larger size tubing to fit around the entire outer jacket ( slide tubing over and out of the way for later). Use the appropriate size shrink tube for the shield.
Image 2: Shrink over the shield wire leaving the same length of exposed wire.
Image 3: Size and cut tubing sleeves for XLR pins 1-2-3 and set aside.
NOTE: Its strongly recommended NOT stripping off shrunk tubing on tinned wire. it will not remove as easily as the factory jacket and likely create a do-over.
Step 4: Tool and Procedure
1- Place one XLR tube sleeve on your first wire and seat so its even with wires jacket and hold.
With your tool: slide it into the tubing with wire and adjust until all holds firm and enough for slight lifting.
NOTE: Position and clamp-down the connector from moving.
Preference TIP: Ive bought all the contraptions and made jigs to aid holding things down while soldering and all stunk just getting in the way.
A good needle nose vice-grip with a couple large spring clamps always worked best in the end, just be sure not to crush connectors and shrink tube over vice-grip tips to avoid scratching (use clear, it just works best).
Step 5: Procedure Continued
1- Lift and solder the wire into place, allow solder joint to cool several seconds before removing tool. when ready to remove tool, gently lift and or twist to stretch the tubing if necessary. the tool leaves the space to recover though the tubing has likely shrunk.
2- Slide the recovered tubing into-place and shrink.
3- Repeat steps for all wires.
4- When done, slide forward the tubing placed on wire earlier and shrink as shown.
FYI: Heat Shrink Tube is very resilient and will bounce right back when re-heated, even after multiple stretches.
Note: its important not to make the slightest cut or nick on the tubing ends. it will tear open like a zipper when heated during shrinking.
Folks, its as simple as that.