Since the Flow hive has a non-standard opening and there are no off-the-shelf solutions for entrance reducers out there, I had to make my own.
I cut three of the starter strips to the width of the opening and then glued them together.
After 24 hours, I cut out the notch with a boxcutter.
I had to sand the block down about a millimeter to fit it w/o raising the brood box.
Great job, and what about a couple of knobs or handles so you can remove if the weather gets warm?
There’s a thought, but with a screened bottom board, ventilation may not be too much of an issue.
Little knobs would be a welcome addition though no matter what.
I use my J tool/Hive tool
Ventilation may not be the issue, but when your hive gets busy, you might want an entrance 5 times that size! In any case, you have another 5 starter strips that you want to use on something, don’t you??? 
Otherwise, I love your work - simple and effective.
Hi Bobby, I have one tip for you. Make sure your entrance reducer is a firm fit, otherwise if the bees don’t like it, they’ll push it out.
Hi Bob… I made similar entrance reducer. I didn’t care for the loss fit of a purchased on I bought sometime ago.
here’s just couple pix’s of mine I made. It nice to be able to make or modify our equipment. Keep it up.Take care n happy beekeeping,
Gerald
I bought one and have made the rest so I can whittle them down to size - but I like the idea of using the wooden Starter strips - thanks for the tip
Hey, i have heard of the same thing, bees pushing out entrance reducers. Does this mean it would be advisable to give them that choice? They may feel the need to improve ventilation, and we are forcing them to reduce ventilation?
I think I would prefer an entrance reducer the bees can choose 
No possibility of the bees pushing this one out - it is quite snug.
This Saturday when I pick up my nucs, the AM temperature will be in the upper 30’s to low 40’s. (4-ish degrees Centigrade). I am going to have to wait until later in the day after it warms up to transfer them into the hive
The lower temperature expected over the next few days plus the need to give the girls a smaller entrance to protect as they get up to speed dictates my decision to have the entrance reducer in place.
Hi Phillip, I’m not really sure if they push them out to get more air flow or if they merely push them out because they see it as a foreign body.
I just think you need to use the entrance reducer that’s appropriate for your climate. I used them when I first started beekeeping, now I don’t bother. Ideal if your looking to harvest some propolis because if we don’t provide an entrance reducer, they’ll take matters into their own hands & put bridging propolis across the bottoms of the frames.
I just made another bottom board, with some changes to hold a tray and use a standard size entrance reducer
If the bees can “Push Out” the reducer it was not very tight or you had a rodent in the trying to get out LOL
What would be the best method to cut two slots but wider, top slot for the bees (7-10mm) and a bottom slot for small hive beetle (2.5mm)? You have given me an idea! Do you cut with a handsaw and then chisel it out or is there another way?
That is how I did it
Oh no! I am just assembling my hive and getting my bees. is this entrance reducer essential?
In the UK entrance reducers are mainly used at the end of the season and winter. This is to help the bees protect against Wasps in late season and Mice and other small rodents in winter who find nice warm hives appealing.
If you have a new hive or a small swarm or a new Nuc - people do reduce the entrance to help the guard bees have a smaller area to defend.
When the hive is in full swing a reducer is not necessary but personal choice for some
Does that help? @Patti
I had a one on one tutorial with a seasoned beekeeper last week. I love the eagerness and inventiveness of us newbies (I think we are referred to as Beeks by the veterans). But I also love the tips and experience that seasoned bee keepers share. Catalogs are full of cool things that make us think we need them when in fact we probably don’t.
I learned that stuffing the entrance with newspaper for a day is all that is needed to keep newly installed bees from taking off rather than settling in. He goes back out a day later to remove some or all of the paper. Often times he finds that they have chewed a small exit anyway.
What is the exact dimension difference between a standard reducer and a reducer that would fit a Flow hive? Is it too tall too short etc?
The Flow hive entrance is less high than a standard Lang. I will try to get some measurements - traveling atm, but I may have some photos in a file somewhere.
