equipment that’s specified.
» The exact proportions of oil and sodium
hydroxide (NaOH) are extremely important for safety reasons. Excess NaOH
can remain, and the pH of the soap is not
tested. When you get NaOH on your skin, it
feels soapy (it’s actually making soap from
the fatty acids in your skin); this is worth
explaining so people know they might have
got some on them.
» It’s true that the amount of NaOH used in
your method should not be enough to react
with the all of the oil completely; this is
itself a safety precaution, because in theory
all the NaOH will be used up. But the type
of oils used shouldn’t be changed, as this
would alter the amount of NaOH required.
» Any mistakes made during this process are
much more serious than any “toxins” found
in off-the-shelf soap.
—Zac Watts, Melbourne, Australia
I’m not impressed with the homemade
Nerf blaster in Volume 29 [“Better Nerf Gun”].
There’s an online community that has tackled this problem in ways that are far easier.
Not every maker has a lathe, and using metal
racks up the cost and difficulty. A better blaster can be built for $20 out of PVC pipe and
fittings by a newbie with a Dremel, and gets
ranges of 60ft to 80ft. Heck, even a well-made
HAMP (High Airflow Manual Plunger) gets
60ft, and it uses yarn for the seal! I’m disappointed that the novice maker was ignored.
—Daniel Seyler, Pocahontas, Illinois
EXECUTIVE EDITOR PAUL SPINRAD REPLIES: Thank you
for writing. I think our Nerf gun is beautiful, but it does
require metal lathing, wood shaping, and other operations
that aren’t quick or easy. Is there a quick PVC Nerf blaster
or HAMP you’d recommend? An easily built high-perfor-mance PVC Nerf dart blaster sounds really fun.
DANIEL SEYLER REPLIES: The HAMP is one of the most
basic NERF guns, originally documented on NerfHaven
( nerfhaven.com) by member Kane TheMediocre. You can
build one for $10 in less than an hour!
I own a toy store and have been pushing
the educational power of toys for decades
[Volume 28, “A Curriculum of Toys”].
“Toy learning” is very right-brained, all about
patterns and relationships. Most classroom
learning is left-brained, all about labels and
logic and rules. There are schools that are
finally realizing just how much of the right
brain we leave untapped in our schooling process (other than fine-arts programs), and are
now starting to incorporate more discovery
into regular academics.
It is just my opinion but your magazine is
the best magazine out there. When I read the
Robots issue (Volume 27) I really wanted to
build those robots and possibly merge them.
In the Toys and Games issue (Volume 28)
I wanted to build the catapult really bad. The
instructions for the projects are good at telling
me what to do, and you seem to include the
blueprints that I need to build a device right
away. Thank you for publishing such an awesome magazine.
Volume 29’s Country Scientist column stated that
“Water vapor ... alone keeps the Earth warm enough to
prevent the entire planet from freezing.” In fact, while
water vapor is the gas most responsible for the greenhouse effect, it is not sufficient to prevent “snowball
Earth” conditions — that requires CO2 as well.
Also, we may have implied that air temperatures
decrease with altitude because the air is dryer, when
the opposite is true: the air is cooler at altitude
because of lower pressure, and it’s dryer because
cooler air holds less vapor.
Thanks to reader Christopher Hogan for spotting
the errors, and to Dr. Gavin Schmidt of the NASA/
Goddard Institute for Space Studies for setting the
In the schematic for Volume 26’s “Luna Mod” sound
looper, the labels for Tempo and Sound were mistakenly reversed. The corrected schematic is online at
makezine.com/26/lunamod and makeprojects.com/
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