If the files are too big it won't pack them in one large file, you'll need to create a multi chunk file, you have to do that from the command line, change to your black mesa bin folder and enter a command like this

vpk -M -c 200 c:\path\custom map folder (chunk size in MB, replace 200 with whatever you want the chunk size to be. Don't go over 400MB).

It'll place the VPK in the same place as the original folder if it outputs correctly.

im having trouble with getting the vpk putting my folder into the vpk.exe wont work or wont change anything

thank you

Additionally, if you want the map to appear in the workshop menu, you also need a \campaigns folder with an addonname.json file and a \campaigns\images folder with a preview image. The contents of the JSON file will look something like this

{
"author": "Shane Phillips",
"url": "",
"title": "Sewer",
"description": "",
"imageSource": "image://game/campaigns/images/sewer.png",
"chapters": [
{
"title": "Sewer",
"description": "",
"imageSource": "image://game/campaigns/images/sewer.png",
"levelName": "bm_sewer"
}
]
}

There's a good tutorial for packing maps and addons here:

https://cdn.akamai.steamstatic.com/steam/apps/362890/manuals/bms_workshop_guide.pdf?t=1457150783

how do you publish maps

oh you know i'm gonna add a ton of npcs and crash my game in this map