@epoletna Go check out form1suppressor.boards.net TONS of information there on building your own suppressor. Just make sure to read everything you can prior to asking questions as most everything you would want to know is already on the site. The "Tutorial" on the site has a lot of good basic information, but some of it is outdated as you will read in other threads about suppressor design, baffle clipping etc. (IE: using the DHC baffle clip method).
As others have mentioned it is ok to have the un-assembled/un-drilled parts in your possession prior to receiving your stamp, just do NOT drill anything including the end cap prior to receiving your stamp. Doing so can constitute "constructive intent" and as others have mentioned the penalties are butt clenching. Current efile approvals are running between 20-40 calendar days from time of filing. I submitted my current trust efile form 1 on 2-6-20 and received approval on 3-9-20 and this included rolling my own prints and mailing them to the NFA. Several sites such as
https://www.nationalguntrusts.com/ have a walk thru on how to efile as an individual or a trust to make the process simple.
As far as companies that make unassembled solvent traps, Nick over @ ecco doesn't supply full trap kits for you to assemble. He can make your individual parts or as an SOT he can "recore" your existing can as well as making brakes, adapters etc. I had him make my adapter for my Maverick tube, 2 helical brakes and currently have sent off my tube, adapter and end cap for engraving and Moly Resin coating. Great communication and outstanding quality imo.
While DM is one of the top manufacturers of quality parts, you WILL be waiting awhile for your items to arrive. If you purchase from him just go in with the attitude of "buy it and forget it" and you will be happy once it actually arrives. There are several other suppliers who have quality parts depending on what caliber host you will be using. I've sourced items thru several companies as well as individuals. When they have them in stock, Maverick precision has some great quality tubes and internals especially if you are considering a centerfire rifle build. Here are a couple links to places that USUALLY have items in stock in reasonable time frames as well as quality parts depending on application:
maverickprecision.com
diversifiedmachine.us
Premium Stainless and Titanium and Components For Commercial, Industrial, Art and Food Service Industries, and Components for the Home Hobbyist We provide the very best products and customer service Most of our components are in stock and ready for shipment. We custom machine all tubes in house...
superprecisionconcepts.com
SD Tactical Arms is veteran owned and operated by the Kress family. Founded in 2012, SDTA does its own work custom design to in-house machining.
sdtacticalarms.com
If you want more info here, post what caliber(s) you are thinking of suppressing, host gun and length and I will try to help any way I can. Good luck!