How to Make a Mantle with a Hidden Compartment

John Malecki

How to Make a Mantle with a Hidden Compartment

A Step-by-Step Guide to Building a ‘Hidden in Plain Sight’ Mantle

min read
Oct 7, 2018

Not long ago, I began the full-on destruction of my living room for a remodel. While sticking to the modern rustic vibe that I love, I wanted to find a way to really make my gorgeous fireplace pop. Knowing that a good mantle can truly make or break a fireplace, I knew this was a project I wanted to tackle myself.

I took this mantle project as the perfect opportunity to try out a hidden compartment - something I’ve been dying to do for months now. As the big, jolly 2nd-amendment-loving dude that I am, I thought this would be a great place for a ‘hidden in plain sight’ spot for my gun. I’ll throw that guy right in the living room hidden under my nose, just in case anyone plans on messing with a 6’2”, 275-pound man like myself.

I decided to use some beautiful reclaimed wood to build this hidden compartment mantle out. I included a child-safe lock and a place for a few rounds and couldn’t be more hype about how this thing turned out. Take a look.

Project Overview:

How to Make a Mantle with a Hidden Compartment

  1. Cut down your wood
  2. Create forms for epoxy filling
  3. Pour epoxy in the voids
  4. Plane the top and back faces
  5. Glue up the mantle
  6. Cut fold-down compartment
  7. Route and plane the front surfaces
  8. Mount the hidden door
  9. Install childproof lock and velcro
  10. Sand and finish

What You’ll Need:


  • Reclaimed wood - I use a beam that is comprable to my fireplace. A 6” x 6” x 50” Final dimension
  • Safety lock
  • Hinges
  • Epoxy


  • Jointer
  • MAP Gas
  • Router

You’ll also need a variety of other woodworking tools - check out some of my faves.

This page contains affiliate links, but all ideas are my own. For more information, check out my disclosure page.

How to Make a Mantle with a Hidden Compartment: the Step by Step

Cut down your wood

Get started by cutting down your wood for the top, sides, and front, and back of the mantle. I chose some reclaimed wood for this project to give it that modern rustic vibe I’ve been going for in my decor. I did this with a joiner and a band saw and cleaned up the rough faces as needed.

Create forms for epoxy filling

Because this wood is reclaimed, it has some cracks and voids in it. I figured I could fill these voids with some epoxy to create a nice surface. To do this, I created some forms out of scrap wood, lining them with masking tape for a water-tight seal. 

Pour epoxy in the voids

Once the forms were built, I put my wood inside and filled the cracks with epoxy that I dyed black. Let this cure for at least 72 hours, then carefully break your slabs out of the molds.

Plane the top and back faces

Once the epoxy is cured and solid, plane down your top and back faces for your mantle. You want these to have a really nice, flat finish to maintain the modern look, so this step is really important for getting the finished product you’re looking for.

Glue up the mantle

Once your parts are planed, it’s time for glue up. Start with the side blocks first, working up and around to a level finish. Clamp these together and allow the glue to dry completely.

Cut fold-down compartment

While your glue is drying, you have the perfect opportunity to cut your fold-down compartment door. Get a good measurement of your mantlepiece, cut your door to size, and plane it to the perfect thickness.

Route and plane the front surfaces

You’re likely to have some overlap of your top piece and the front surface. I did this on purpose to get a nice grain match-up. However, I had to go in with a router and hand plane to get these edges flush together for a seamless front surface. While you’re doing this, take the time to cut each of the sides down to size as well.

Mount the hidden door

Next, it’s time to mount the hidden door. I did this with a simple hinge, cutting out a small block to mount the hardware on. Test to make sure your door swings open and close with easy, sanding down and rough points of contact by hand.

Install childproof lock and velcro

Because my gun will be kept in the mantle, it was important to me to make sure this thing locked safely. I used a two-piece magnetic lock. If I needed to unlock the compartment, I’d need to know where the other half of the magnet is and align it in the proper spot. This worked like an absolute charm.

I also routed out a small groove to keep a handful of shotgun shells on hand outside of my gun. I used velcro to secure both the shells and my gun into place.

Sand and finish

Finally, it’s time to sand and finish her off! I sanded the whole thing down to 220 grit and applied the finish by hand to pull out the beautiful color and grain of the wood. Once dry, I mounted the mantle right on my fireplace and could not be more pleased with how it looks.

If you liked this project, Check out some other home projects!

Download the Plan

Want to try this build out for yourself? Download the digital plan now for step-by-step instructions, measurements, and a detailed look at how to punch this project in the face.

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min read
Oct 7, 2018
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John Malecki

I used to be an offensive lineman in the NFL, Now I run my own furniture business and am completely self taught. In my videos and posts you'll see a variety of wood and metal work as well as some tips and tricks. Enjoy!