Key Takeaways
From the create screen pick Build a custom fund. Give it a name, an optional description, and an optional benchmark ticker such as SPY for the performance comparison. Then choose a starting point:

Search by ticker or company name and add each stock. Every result carries a compliance badge, and blocked stocks from your blacklist are marked.

Set a percentage per holding. The bar at the top shows the total. Three shortcuts help:
Warnings appear here for doubtful or unrated holdings and for weights that do not sum to 100. Press Save custom fund. As with filtered funds, saving places no trades.

Edit holdings in the fund's action menu reopens the builder. Compliance is re-checked on every save.
Open the fund's action menu and choose Share fund, then Enable sharing. You get a public link. Anyone who opens it sees the holdings, sector mix, and performance comparison, and can copy the fund into their own account. Copies can stay linked so your later edits sync to them, or be forked into an independent fund.
Swipe to see all 2 screens
Disable sharing stops the link working. Existing copies keep their last synced holdings.
A stock will not add. It is not tradable on Alpaca, or it is on your blacklist. The badge tells you which.
Weights keep showing a warning after I scale. Rounding can leave the total at 99.9 or 100.1. Adjust one holding by 0.1.