How do I create an LPC-LINK? ...so that I can use the LPCXpresso IDE in full when developing for my own design.

Option 1a: Buy an LPC-Link 2 board. Note that LPC-Link 2 firmware in combination with the LPCXpresso IDE supports the Cortex-Mx cores in the LPC family, but not the older ARM7/ARM9 cores.

Option 1b: Buy an LPCXpresso V2 board and use the on-board LPC-Link 2 compatible debug interface on this board. It is possible to disconnec the target MCU on these boards and connect to a custom board MCU instead. Note that the same restrictions as above applies here (ARM7/ARM9 cores are not supported).

Option 2: Buy an original LPCXpresso board and separate the LPC-Link side from the target side. Then use the separated LPC-Link side as the JTAG/SWD interface. Follow this instruction how to rework an LPCXpresso board.