Started a new one today on one of those closeout All Sar blanks. Got parts for split grip fabricated/shaped. Made some small modifications to Fuji ACS seat. Shortened threaded end-lock reel down tight and all you can see ahead of the nut is the aluminum winding ck. I'm using instead of a foregrip. Looks neat. Goal is as close to 4oz. as possible. Weighed blank,seat,grips,guides and I'm at 3.78oz. I believe glue, wraps and finish will push me past 4. Sure do like my digital scale I got from Harbor Freight on sale for $12.95

A man's gotta believe in something; I believe I'll go fishing.

Depending on what you are building you might consider going to Micro guides. That would cut down on you guide, thread and epxy weight. maybe bringing you in under 4oz.

Loose the winding check too. Less weight. Only there for looks.

Permagloss would also cut down on the finish weight if you use just enough to protect the thread. There is nothing lighter than a hole you could take some of the flat seat area under your reel's foot away making a slot without much problem.
All this is mute if you don't use the lightest reel you can find/afford.