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This post is one of several resources I created for students in my Klum House Bag Lab at Modern Domestic. Find the full series of blog posts here.

Klum House bags call for 5–10 oz leather straps because thicker leather is more durable and less prone to stretching out over time. However, this weight of leather is generally too thick to sew through with a domestic sewing machine, so Klum House bag straps are attached with rivets and other metal hardware.

Basic Tools

Work Surface

stable surface to reduce bounce-back
less important for punches, but essential for setting hardware

Mallets and Mauls

While you can use a regular hammer to strike your tools, a non-metal maul or mallet will considerably extend the lifespan of your tools.

Bakelite, rawhide, poly, wood
Do NOT use a rubber mallet—they aren’t strong enough to set hardware and create bounce-back that makes it difficult to get clean results when punching, setting, and stamping.

bakelite mallet 13 oz
mallets: tend to be lighter, can use longer without fatigue
mauls: tend to be heavier, good for setting hardware
Weighted vs non-weighted

Punches

Punching Tips

Always place a punching board underneath your work when punching to protect your tools and table. The cutting mat you use with a rotary cutter is NOT sufficient. I prefer to use a small poly punching board, but you can also use a plastic cutting board (I wouldn’t use it for food after punching on it, since the dents will make it harder to clean) or a couple layers of cardboard.
If your punch directly strikes a hard surface, you will dull the cutting edge and will not be able to use it unless you resharpen it. It is possible to resharpen punch tools, but it’s not trivial. If you don’t already own sharpening tools, it’s probably more cost-effective to replace dulled punches.
Keep your punch tool vertical when striking with a mallet.

Punching Holes

To install hardware on your bag, you will first need to punch holes through the fabric and leather. A simple awl can be used to create holes in paper pattern pieces or fabric. To punch holes in fabric and leather that are accurately sized for your hardware, you will want to invest in drive punches and/or a rotary punch.

A drive punch creates a holes with a set diameter and is used with a mallet/maul over a punching board. Drive punches are cheap, easy to use, and can punch holes in hard-to-reach places.

If your punch doesn’t seem to be working, try clearing the tube with an awl or other pointed tool.

A rotary punch contains several tubes with various diameters. It is operated by squeezing with both hands. Rotary punches are convenient: they contain several tools in one, and there’s no need to use a mallet. However, since the are limited by the depth of the neck, they are best for punching holes near edges.

Even if you choose to invest in a rotary punch, I recommend buying at least one drive punch so you can access spots that the rotary punch cannot.

When punching through multiple layers of fabric, work slowly and triple-check that you will not accidentally punch through other areas of your bag. Move excess fabric out of the way or place the punching board inside your bag, pocket, etc. to protect the layers underneath.

For bags with a lining and zipper closure: before punching holes for the straps, tug the lining down away from the top of the bag to ensure that the lining doesn’t bubble up and obstruct the zipper.

I usually punch holes in leather from the right side for a clean finish. Occasionally, you may need to re-punch the holes from the wrong side so the hardware can pass through more easily.

If you buy a Klum House kit—either the full maker kit or the leather and hardware kit—all of your leather will be cut to size and pre-punched. That said, I’ve found that in some kits the holes punched in the leather are not large enough for the hardware provided and need to be widened, so it may be worth adding at least one punching tool to your toolkit.

I recommend buying all of your tools in whatever measurement system you prefer.
In general, err on the side of punching smaller holes, especially with fabric! Holes punched in fabric stretch/widen over time to a greater degree than holes punched in leather. You can always widen holes if needed.
Klum House provides diameters in fractions of an inch. If the

Choose rotary punch barrel with closest diameter to hardware stem/post. use two hands.

match up stem of rivet with drive punch barrel

	Imperial: Fraction	Imperial: Decimal	Metric
Fabric	3/32”	0.09375”	2.38 mm
Leather	1/8”	0.125”	3.18 mm
Chicago Screws	3/16”	0.1875”	4.76 mm

Strap End Punches

If you plan to make a lot of bags, it’s more cost-effective to buy lengths of leather strap and cut them to size yourself. You can use a rotary cutter and ruler to trim the ends of your strap straight or at an angle, but if you prefer a rounded end (or another shape), purchase an end strap punch that is at least the width of the strap you will use it on. Center the punch over the end of the strap with a punching board underneath and strike it a couple times with a mallet. Do your best to hold the punch vertically (perpendicular to the strap) so the edge of the leather doesn’t show on the right side. If needed, use sandpaper to smooth the cut edges and burnish if desired.

Setting Hardware

use the correct hardware and the appropriate size for your project
don’t forget the leather reinforcement pieces!
set it correctly
hard surface, no bounce
leather sandwiching fabric so hardware doesn’t pull through bag
use appropriate sized hardware for the thickness of your material

may need to flatten washers

When setting hardware, work on a hard, stable surface with minimal bounce. Use a stone slab or metal anvil on top of a sturdy countertop or concrete floor. sturdy, hard, and smooth

no metal anvil? can use side of a hammer

Use double-sided tape in the dot anvil to keep the cap steady
Remember to add leather reinforcement tabs and washers as instructed. Leather reinforcement strengthens the bag’s stress points. Rivets will not set correctly without the proper thickness of leather.

Can trim the rivet down to size using the cutter tool thing

Sandwich fabric between 2 layers of fabric else hardware will eventually wear thru fabric
punch smallest hole possible
metal tools will last longer if you use a mallet
rubber mallets will not set hardware > will not transfer enough force
pair thickness of work with length of hardware stem

stem sticking up too high > stem will be crooked, not a strong attachment
stem too low? might not catch the other piece of hardware (or leather, for tubular rivets)

start with light tap and once it starts to set you can add more pressure; don’t want to push the hammer sideways while hammering or it’ll set crooked.

head of rivet should indent into leather

hammer from inside in case you miss and dent it, that way it’s on the inside

stem from inside, lay strap on, add cap

industrial hand press with double cap rivet die

How thick is your material?
How much stress will this spot take?
What look are you going for?

SAME STRAP GOES ON SAME SIDE OF BAG! MAKE SURE STRAP IS NOT TWISTED!

leather washers prevent fabric from tearing over time

Removing Hardware

removing rivets: rivet removal tool

pliers and angle cutter: use two sets of pliers to pull leather and try to open up some space to access rivet. choose side of leather that will be less obvious if chewed up, then insert angle cutter and cut the post. can also use pliers directly on the cap of the side you’re trying to cut. make sure your hand/body is out of the path of the angle cutter in case it slips. point the cap away from you because it’ll fly

Hardware Types

rivets

double-capped rivets

tubular rivets

snaps

line 24 snaps

magnetic snaps

magnetic snap rivets

screws

chicago screws

rings

d-rings

o-rings

split-rings

hooks

swivel hooks

Photo by cottonbro studio

Keep In Touch

Thanks very much for reading! If you’d like in-person support and instruction, please sign up for my classes at Modern Domestic or reach out to schedule a private lesson. If you have any questions, feedback, or corrections regarding this post, please don’t hesitate to contact me!

bag lab: tools & hardware