I have a Fenwick HMX 7' ML.  I have loved the models before this one but this one is HEAVY!  completely tip heavy and I can't fish with it.  I bought it for finesse techniques <1/8oz so the tip weight is a real problem.  I pulled all the guides off because they were cheap and heavy, very heavy.  I want to replace it with recoil guides or something similiar.

The question is that with only the tip guide, the rod is still forward heavy.  Can i add weight to the butt or something?

Yes, there are a few ways to add weight to the butt.  The simplest is stainless washers in a crutch tip.  I prefer to add weight inside the blank or to use a weighted butt cap.

is adding weight a common practice for rod building?  Just wondering if I should ditch the blank.

if you are gonna keep the blank , put some size 3 micro guides on it , assuming it's a casting rod , should balance it out .

if it's a spinning rod , i'd look into a micro guide set up too , i have a Phenix M1 7'8'' MXF rod with micro guides and it isn't tip heavy enough to be noticeable ..

Yes, balancing a Rod with extra weight in the butt can make a huge difference in how it fishes and feels.  I made a flipping stick that was hugely tip heavy and was tiring to fish.  Cut off the butt cap and added lead weights until it balanced with the reel I used with it.  Huge difference in how it handled and there was no fatigue fishing with it.  The extra 1+ oz of weight seemed like a lot when I did it but supporting the extra overall weight was unnoticeable while fishing and the balanced Rod/reel combo is a pleasure to fish.  This applies only to rods that are used for bottom contact presentations, not to rods used for moving presentations which are tip heavy anyway while fished.

If you fish alot of slop (versus grass), or fish in temps below freezing I would avoid micro guides.

 

Full disclosure,  I haven't,  don't plan on and won't use micro guides. I feel they limit your line options ( for instance using braid with a bite leader) Even using straight braid in grass or slop can cause the guides to choke.

 

Most tourney fishermen I know have either re-wrapped or replaced their micro guide rods. ....

 

But,  it's your rod. Do what WORKS for YOU! !!!!

Go to Getbit and look at "butt caps" Under that you will find some weighted butts and some adjustable weighted butt caps.  The adjustable kit only costs $3.19 so it is a cheap option.