I think I did as part of my DIY sex toys series but search doesn’t work even on my own content now so I had a look but can’t find it either.
If I recall it was by cutting the end off a standard syringe, then carefully smoothing the edges. Use some lube to create better suction and slip it over your clit, CAREFULLY pulling the plunger up bit by bit.
If you want other non-obvious items I’ve seen snakebite sucker things that people use for this too. You can get them on ebay.